Re: Practice question
On Mon, 06 Oct 2014 22:06:09 -0400, Seymore4Head wrote: On Tue, 7 Oct 2014 01:46:37 + (UTC), Denis McMahon denismfmcma...@gmail.com wrote: On Sun, 05 Oct 2014 19:02:31 -0400, Seymore4Head wrote: For the record, I don't want a hint. I want the answer. I see a practice question is similar to this. 15 = x 30 And it wants a similar expression that is equivalent. I think part of the problem here is that you don't understand the expression. The expression: 15 = x 30 contains two conditions: 15 = x x 30 For the whole expression to be true, both conditions must be true, hence the equivalence is: (15 = x) and (x 30) to test this in python command line, see if the two different expressions give the same result for a suitable range of values of x: for x in range(50): if not (15 = x 30) == ((15 = x) and (x 30)): print discrepancy or for x in range(50): if (15 = x 30) == ((15 = x) and (x 30)): print ok All of the practice questions up to this question had 4 answers. With each question you could verify the correct answers by just copy and pasting each choice into Python. So when the instructions said I could verify this with Python I assumed there might be some way to test if the question was == to each answer. no you need to type in each snippet of code see if they give the same result when run. -- In every non-trivial program there is at least one bug. -- https://mail.python.org/mailman/listinfo/python-list
Re: Practice question
On Tuesday, October 7, 2014 2:19:39 AM UTC+5:30, Steven D'Aprano wrote: I have fewer issues with your conclusion and analogy than I do with the basic premise that there is a connection between Seymore's problem here and the use, or non-use, of print in the interactive interpreter. I don't see how replacing interactive use and/or the use of print with functions containing return statements would help Seymore. The issue is not only that print is bad but that the interpreter is good for learning and trying out. Are these two really unconnected. Lets see... One can - use print without the interpreter - use the interpreter without print - use both But can one use neither? [Assuming telepathy/ESP etc is disallowed] So pushing beginners away from print can push them up the learning curve more quickly -- https://mail.python.org/mailman/listinfo/python-list
Re: Practice question
On Thu, Oct 9, 2014 at 3:14 AM, Rustom Mody rustompm...@gmail.com wrote: The issue is not only that print is bad but that the interpreter is good for learning and trying out. Are these two really unconnected. Lets see... One can - use print without the interpreter - use the interpreter without print - use both But can one use neither? [Assuming telepathy/ESP etc is disallowed] So pushing beginners away from print can push them up the learning curve more quickly (Please be more clear with your terminology; running Python scripts is still using the interpreter, it's just not using *interactive* Python. What you're saying above is all about Python's interactive mode.) Your conclusion doesn't obviously follow from your preceding statements. How does pushing people away from print push them up? Which way is up? Is it up to move from interactive Python to scripts run from the command line? Or is that down? How does the avoidance of print push anyone anywhere, anyway? ChrisA -- https://mail.python.org/mailman/listinfo/python-list
Re: Practice question
On Wed, Oct 8, 2014 at 11:14 AM, Rustom Mody rustompm...@gmail.com wrote: So pushing beginners away from print can push them up the learning curve more quickly Or more quickly discourage them. I still use print for all sorts of things. In my opinion, there is often no need for fancy loggers, str.format, or the write method of file-like objects. Print will often get you a good enough result faster than the other means. Skip -- https://mail.python.org/mailman/listinfo/python-list
Re: Practice question
On Wednesday, October 8, 2014 9:58:11 PM UTC+5:30, Skip Montanaro wrote: On Wed, Oct 8, 2014 at 11:14 AM, Rustom Mody wrote: So pushing beginners away from print can push them up the learning curve more quickly Or more quickly discourage them. I still use print for all sorts of things. In my opinion, there is often no need for fancy loggers, str.format, or the write method of file-like objects. Print will often get you a good enough result faster than the other means. Well I'm not talking of people like you!! Nor of more sophisticated tools than print. I am talking of the fact that an absolute basic sine qua non for beginners is to be able to structure programs: - breaking up a complex expression into sub-expressions - abstracting out a sub-expression into a function with an appropriate parameterization - inverses of the above when the current cut is sub-optimal etc etc... what is nowadays fashionably called 'refactoring' And for that the noob needs to learn to write return-ing function where he currently writes a print-ing function. -- https://mail.python.org/mailman/listinfo/python-list
Re: Practice question
On Sun, 05 Oct 2014 20:07:50 -0400, Seymore4Head wrote: Here is the exact question, I was trying to post something similar. I failed. http://i.imgur.com/iUGh4xf.jpg Please don't post screen shots if you can avoid it. You almost certainly can copy and paste the text from the web page. And if you can't, you can usually re-type the question. It's good practice to strength your typing skills. Screen shots cannot be read by people using a screen reader, or who don't have access to the web (but are reading their mail), or if the host site (in this case, imgur) is down or blocked. -- Steven -- https://mail.python.org/mailman/listinfo/python-list
Re: Practice question
On Sun, 05 Oct 2014 20:18:13 -0400, Seymore4Head wrote: I think I get it now. You are using a sample of answers. So you could actually just run through them all. (I haven't tried this yet) for x in range(lo,hi) print((15 = x 30) == (15= x and x 30)) Yes, except using print is probably not the best idea, since you might have dozens of True True True True ... printed, one per line, and if you blink the odd False might have scrolled off screen before you notice. With two numbers, 15 and 30, all you really need is five test cases: - a number lower than the smaller of the two numbers (say, 7); - a number equal to the smaller of the two numbers (that is, 15); - a number between the two numbers (say, 21); - a number equal to the larger of the two numbers (that is, 30); - a number higher than the larger of the two numbers (say, 999); The exact numbers don't matter, so long as you test all five cases. And rather than printing True True True... let's use assert instead: for x in (7, 15, 21, 30, 999): assert (15 = x 30) == (15= x and x 30) If the two cases are equal, assert will do nothing. But if they are unequal, assert will raise an exception and stop, and you know that the two cases are not equivalent and can go on to the next possibility. -- Steven -- https://mail.python.org/mailman/listinfo/python-list
Re: Practice question
Steven D'Aprano wrote: With two numbers, 15 and 30, all you really need is five test cases: My solution assumed integers also, but after I posted it, I thought: What about floating points? On Tue, Oct 7, 2014 at 1:48 AM, Steven D'Aprano st...@pearwood.info wrote: On Sun, 05 Oct 2014 20:18:13 -0400, Seymore4Head wrote: I think I get it now. You are using a sample of answers. So you could actually just run through them all. (I haven't tried this yet) for x in range(lo,hi) print((15 = x 30) == (15= x and x 30)) Yes, except using print is probably not the best idea, since you might have dozens of True True True True ... printed, one per line, and if you blink the odd False might have scrolled off screen before you notice. With two numbers, 15 and 30, all you really need is five test cases: - a number lower than the smaller of the two numbers (say, 7); - a number equal to the smaller of the two numbers (that is, 15); - a number between the two numbers (say, 21); - a number equal to the larger of the two numbers (that is, 30); - a number higher than the larger of the two numbers (say, 999); The exact numbers don't matter, so long as you test all five cases. And rather than printing True True True... let's use assert instead: for x in (7, 15, 21, 30, 999): assert (15 = x 30) == (15= x and x 30) If the two cases are equal, assert will do nothing. But if they are unequal, assert will raise an exception and stop, and you know that the two cases are not equivalent and can go on to the next possibility. -- Steven -- https://mail.python.org/mailman/listinfo/python-list -- https://mail.python.org/mailman/listinfo/python-list
Re: Practice question
14x=29 On Sun, Oct 5, 2014 at 4:14 PM, Ned Batchelder n...@nedbatchelder.com wrote: On 10/5/14 7:02 PM, Seymore4Head wrote: For the record, I don't want a hint. I want the answer. I see a practice question is similar to this. 15 = x 30 And it wants a similar expression that is equivalent. So the right answer is 15= x or x 30 No, 15 = x 30 is equivalent to 15 = x and x 30. but one of the other answers is not (15= x and x 30) You are speaking ambiguously. Which did you mean: a) one of the other answers isn't 15 = x and x 30, or: b) one of the other answers is not (15 = x and x 30) ? -- Ned Batchelder, http://nedbatchelder.com -- https://mail.python.org/mailman/listinfo/python-list -- https://mail.python.org/mailman/listinfo/python-list
Re: Practice question
On Sun, Oct 5, 2014 at 9:47 PM, Rustom Mody rustompm...@gmail.com wrote: Sorry Seymore if this sounds condescending -- its not a complaint against you but against those who treat the print statement/expression as kosher for newbies. So if you're not griping about Seymore's original post, are you griping about my response? It was the one you quoted. And what's with the comparison between use of the print statement and driving on the wrong side of the road? Skip -- https://mail.python.org/mailman/listinfo/python-list
Re: Practice question
On Monday, October 6, 2014 6:34:27 PM UTC+5:30, Skip Montanaro wrote: On Sun, Oct 5, 2014 at 9:47 PM, Rustom Mody wrote: Sorry Seymore if this sounds condescending -- its not a complaint against you but against those who treat the print statement/expression as kosher for newbies. So if you're not griping about Seymore's original post, are you griping about my response? It was the one you quoted. It so happened you were the person to note that here was a question(er) needing instruction about using the interpreter. Nothing wrong with the answer (or the question). Something wrong with the point at which it emerges. And what's with the comparison between use of the print statement and driving on the wrong side of the road? Consider the sequence: 1. Drives on the wrong side of the road 2. Has no clue that there's such a concept as 'wrong side of road' 3. Teaches people to drive without conveying anything about 'wrong side of road' Hopefully you will agree that 1 2 3?? My gripe is with 3 -- https://mail.python.org/mailman/listinfo/python-list
Re: Practice question
On Tue, Oct 7, 2014 at 3:23 AM, Rustom Mody rustompm...@gmail.com wrote: Consider the sequence: 1. Drives on the wrong side of the road 2. Has no clue that there's such a concept as 'wrong side of road' 3. Teaches people to drive without conveying anything about 'wrong side of road' Hopefully you will agree that 1 2 3?? My gripe is with 3 No, I don't agree. Teaching people to drive is separate from teaching road rules, which vary by legislature. I can draw the exact same analogy: 1. Fails to follow proper protocol at a hook turn intersection 2. Has no clue that there's such a concept as a hook turn 3. Teaches people to drive without conveying anything about hook turns. Most of you are probably in state 2, and your instructors were probably in state 3. Neither's a problem, because hook turns don't matter until you come to an intersection where they're used. (And even then, there's often signage.) The complaints you're making are about something that does not matter. There are multiple usage patterns for Python; one is to eschew the interactive interpreter and run everything from scripts. That's fine, there's nothing wrong with it. And then, the nuances of interactive Python are completely insignificant. I don't see that your complaints about print and interactive mode have anything at all to do with this thread. ChrisA -- https://mail.python.org/mailman/listinfo/python-list
Re: Practice question
On Monday, October 6, 2014 10:22:27 PM UTC+5:30, Chris Angelico wrote: On Tue, Oct 7, 2014 at 3:23 AM, Rustom Mody wrote: Consider the sequence: 1. Drives on the wrong side of the road 2. Has no clue that there's such a concept as 'wrong side of road' 3. Teaches people to drive without conveying anything about 'wrong side of road' Hopefully you will agree that 1 2 3?? My gripe is with 3 No, I don't agree. Interesting So you dont agree with: 123 ? Or with My gripe is 3 ? The second would be quite bizarre: I have a headache... Sorry. But I dont agree with that -- https://mail.python.org/mailman/listinfo/python-list
Re: Practice question
On Tue, Oct 7, 2014 at 4:05 AM, Rustom Mody rustompm...@gmail.com wrote: On Monday, October 6, 2014 10:22:27 PM UTC+5:30, Chris Angelico wrote: On Tue, Oct 7, 2014 at 3:23 AM, Rustom Mody wrote: Consider the sequence: 1. Drives on the wrong side of the road 2. Has no clue that there's such a concept as 'wrong side of road' 3. Teaches people to drive without conveying anything about 'wrong side of road' Hopefully you will agree that 1 2 3?? My gripe is with 3 No, I don't agree. Interesting So you dont agree with: 123 ? Or with My gripe is 3 ? The second would be quite bizarre: I have a headache... Sorry. But I dont agree with that Well, hey, I've eaten things that disagreed with me. You'd think that would be purely factual. I ate you! I disagree!. But no, it was the 1 2 3 part that I disagreed with... as I'm sure you were aware. Never let the obvious truth of something get in the way of a good joke :) ChrisA -- https://mail.python.org/mailman/listinfo/python-list
Re: Practice question
On Mon, 06 Oct 2014 10:05:40 -0700, Rustom Mody wrote: On Monday, October 6, 2014 10:22:27 PM UTC+5:30, Chris Angelico wrote: On Tue, Oct 7, 2014 at 3:23 AM, Rustom Mody wrote: Consider the sequence: 1. Drives on the wrong side of the road 2. Has no clue that there's such a concept as 'wrong side of road' 3. Teaches people to drive without conveying anything about 'wrong side of road' Hopefully you will agree that 1 2 3?? My gripe is with 3 No, I don't agree. Interesting So you dont agree with: 123 ? I can't speak for Chris, by my answer is neither Yes nor No, but Mu. http://en.wikipedia.org/wiki/Mu_%28negative%29#In_popular_culture I don't understand what semantics you are giving the symbol. It's not less than, since statements 1, 2 and 3 above don't have a total order or even a partial order. What does it mean to say that Drives on the wrong side of the road is less than Teaches people to drive without conveying anything about 'wrong side of road'? Less than in what sense? Alphabetical order? Less dangerous? Less competent? Less annoying? Less expensive? So, no, I don't agree. Nor do I disagree. I have fewer issues with your conclusion and analogy than I do with the basic premise that there is a connection between Seymore's problem here and the use, or non-use, of print in the interactive interpreter. I don't see how replacing interactive use and/or the use of print with functions containing return statements would help Seymore. Or with My gripe is 3 ? The second would be quite bizarre: If it's bizarre, why do you consider that Chris may mean that? The reasonable thing would be to reject it from contention. I have a headache... Sorry. But I dont agree with that I don't agree that you have a headache. You're obviously lying, acting, delusional, an insentient robot programmed to repeat the words 'I have a headache', a zombie (not the brain eating kind, the philosophical kind), a sophisticated bot (but not sophisticated enough to pass the Turing test), or otherwise faking it. I'm just sayin'... -- Steven -- https://mail.python.org/mailman/listinfo/python-list
Re: Practice question
On Oct 6, 2014, at 4:49 PM, Steven D'Aprano st...@pearwood.info wrote: On Mon, 06 Oct 2014 10:05:40 -0700, Rustom Mody wrote: On Monday, October 6, 2014 10:22:27 PM UTC+5:30, Chris Angelico wrote: On Tue, Oct 7, 2014 at 3:23 AM, Rustom Mody wrote: Consider the sequence: 1. Drives on the wrong side of the road 2. Has no clue that there's such a concept as 'wrong side of road' 3. Teaches people to drive without conveying anything about 'wrong side of road' Hopefully you will agree that 1 2 3?? My gripe is with 3 No, I don't agree. Interesting So you dont agree with: 123 ? I can't speak for Chris, by my answer is neither Yes nor No, but Mu. http://en.wikipedia.org/wiki/Mu_%28negative%29#In_popular_culture I don't understand what semantics you are giving the symbol. It's not less than, since statements 1, 2 and 3 above don't have a total order or even a partial order. What does it mean to say that Drives on the wrong side of the road is less than Teaches people to drive without conveying anything about 'wrong side of road'? Less than in what sense? Alphabetical order? Less dangerous? Less competent? Less annoying? Less expensive? So, no, I don't agree. Nor do I disagree. I have fewer issues with your conclusion and analogy than I do with the basic premise that there is a connection between Seymore's problem here and the use, or non-use, of print in the interactive interpreter. I don't see how replacing interactive use and/or the use of print with functions containing return statements would help Seymore. Or with My gripe is 3 ? The second would be quite bizarre: If it's bizarre, why do you consider that Chris may mean that? The reasonable thing would be to reject it from contention. I have a headache... Sorry. But I dont agree with that I don't agree that you have a headache. You're obviously lying, acting, delusional, an insentient robot programmed to repeat the words 'I have a headache', a zombie (not the brain eating kind, the philosophical kind), a sophisticated bot (but not sophisticated enough to pass the Turing test), or otherwise faking it. I'm just sayin'... -- Steven -- I agree that 123. From a numerical point of view this is correct. The distraction here is the inference that the numbers somehow relate to the statements preceding this conclusion. -- https://mail.python.org/mailman/listinfo/python-list
Re: Practice question
On Sun, 05 Oct 2014 19:02:31 -0400, Seymore4Head wrote: For the record, I don't want a hint. I want the answer. I see a practice question is similar to this. 15 = x 30 And it wants a similar expression that is equivalent. I think part of the problem here is that you don't understand the expression. The expression: 15 = x 30 contains two conditions: 15 = x x 30 For the whole expression to be true, both conditions must be true, hence the equivalence is: (15 = x) and (x 30) to test this in python command line, see if the two different expressions give the same result for a suitable range of values of x: for x in range(50): if not (15 = x 30) == ((15 = x) and (x 30)): print discrepancy or for x in range(50): if (15 = x 30) == ((15 = x) and (x 30)): print ok -- Denis McMahon, denismfmcma...@gmail.com -- https://mail.python.org/mailman/listinfo/python-list
Re: Practice question
On Tue, 7 Oct 2014 01:46:37 + (UTC), Denis McMahon denismfmcma...@gmail.com wrote: On Sun, 05 Oct 2014 19:02:31 -0400, Seymore4Head wrote: For the record, I don't want a hint. I want the answer. I see a practice question is similar to this. 15 = x 30 And it wants a similar expression that is equivalent. I think part of the problem here is that you don't understand the expression. The expression: 15 = x 30 contains two conditions: 15 = x x 30 For the whole expression to be true, both conditions must be true, hence the equivalence is: (15 = x) and (x 30) to test this in python command line, see if the two different expressions give the same result for a suitable range of values of x: for x in range(50): if not (15 = x 30) == ((15 = x) and (x 30)): print discrepancy or for x in range(50): if (15 = x 30) == ((15 = x) and (x 30)): print ok All of the practice questions up to this question had 4 answers. With each question you could verify the correct answers by just copy and pasting each choice into Python. So when the instructions said I could verify this with Python I assumed there might be some way to test if the question was == to each answer. -- https://mail.python.org/mailman/listinfo/python-list
Practice question
For the record, I don't want a hint. I want the answer. I see a practice question is similar to this. 15 = x 30 And it wants a similar expression that is equivalent. So the right answer is 15= x or x 30 but one of the other answers is not (15= x and x 30) But it says.remember you can try this out in the Python shell. How? -- https://mail.python.org/mailman/listinfo/python-list
Re: Practice question
In article h2j33adothf9uctcdp5psqk2cclr019...@4ax.com, Seymore4Head Seymore4Head@Hotmail.invalid wrote: For the record, I don't want a hint. I want the answer. 42. -- https://mail.python.org/mailman/listinfo/python-list
Re: Practice question
On 10/5/14 7:02 PM, Seymore4Head wrote: For the record, I don't want a hint. I want the answer. I see a practice question is similar to this. 15 = x 30 And it wants a similar expression that is equivalent. So the right answer is 15= x or x 30 No, 15 = x 30 is equivalent to 15 = x and x 30. but one of the other answers is not (15= x and x 30) You are speaking ambiguously. Which did you mean: a) one of the other answers isn't 15 = x and x 30, or: b) one of the other answers is not (15 = x and x 30) ? -- Ned Batchelder, http://nedbatchelder.com -- https://mail.python.org/mailman/listinfo/python-list
Re: Practice question
On Oct 5, 2014 6:07 PM, Seymore4Head Seymore4Head@hotmail.invalid wrote: For the record, I don't want a hint. I want the answer. I see a practice question is similar to this. 15 = x 30 And it wants a similar expression that is equivalent. Maybe 30 x = 15 ? Seems more similar to the original expression than the other possibilities. As to how to try it out, bring up the Python prompt, assign various values to x, and keep evaluating the possibilities. To simplify evaluation off a bunch of alternatives, consider defining a function which takes x add a parameter and print out the various expression values. I'd give a concrete example, but don't has a prompt available on my phone... Just my 2¢... Skip -- https://mail.python.org/mailman/listinfo/python-list
Re: Practice question
On 10/5/2014 7:02 PM, Seymore4Head wrote: For the record, I don't want a hint. I want the answer. I see a practice question is similar to this. 15 = x 30 And it wants a similar expression that is equivalent. So the right answer is 15= x or x 30 but one of the other answers is not (15= x and x 30) But it says.remember you can try this out in the Python shell. How? For instance, for x in (10, 20, 30, 40): print((15 = x 30) == (15= x and x 30)) -- Terry Jan Reedy -- https://mail.python.org/mailman/listinfo/python-list
Re: Practice question
On Sun, 05 Oct 2014 19:14:27 -0400, Ned Batchelder n...@nedbatchelder.com wrote: On 10/5/14 7:02 PM, Seymore4Head wrote: For the record, I don't want a hint. I want the answer. I see a practice question is similar to this. 15 = x 30 And it wants a similar expression that is equivalent. So the right answer is 15= x or x 30 No, 15 = x 30 is equivalent to 15 = x and x 30. but one of the other answers is not (15= x and x 30) You are speaking ambiguously. Which did you mean: a) one of the other answers isn't 15 = x and x 30, or: b) one of the other answers is not (15 = x and x 30) ? Here is the exact question, I was trying to post something similar. I failed. http://i.imgur.com/iUGh4xf.jpg -- https://mail.python.org/mailman/listinfo/python-list
Re: Practice question
On Sun, 05 Oct 2014 19:47:40 -0400, Terry Reedy tjre...@udel.edu wrote: On 10/5/2014 7:02 PM, Seymore4Head wrote: For the record, I don't want a hint. I want the answer. I see a practice question is similar to this. 15 = x 30 And it wants a similar expression that is equivalent. So the right answer is 15= x or x 30 but one of the other answers is not (15= x and x 30) But it says.remember you can try this out in the Python shell. How? For instance, for x in (10, 20, 30, 40): print((15 = x 30) == (15= x and x 30)) I think I get it now. You are using a sample of answers. So you could actually just run through them all. (I haven't tried this yet) for x in range(lo,hi) print((15 = x 30) == (15= x and x 30)) Thanks -- https://mail.python.org/mailman/listinfo/python-list
Re: Practice question
On 10/5/14 8:07 PM, Seymore4Head wrote: On Sun, 05 Oct 2014 19:14:27 -0400, Ned Batchelder n...@nedbatchelder.com wrote: On 10/5/14 7:02 PM, Seymore4Head wrote: For the record, I don't want a hint. I want the answer. I see a practice question is similar to this. 15 = x 30 And it wants a similar expression that is equivalent. So the right answer is 15= x or x 30 No, 15 = x 30 is equivalent to 15 = x and x 30. but one of the other answers is not (15= x and x 30) You are speaking ambiguously. Which did you mean: a) one of the other answers isn't 15 = x and x 30, or: b) one of the other answers is not (15 = x and x 30) ? Here is the exact question, I was trying to post something similar. I failed. http://i.imgur.com/iUGh4xf.jpg Why isn't the fourth one correct? -- Ned Batchelder, http://nedbatchelder.com -- https://mail.python.org/mailman/listinfo/python-list
Re: Practice question
On Monday, October 6, 2014 5:04:11 AM UTC+5:30, Skip Montanaro wrote: On Oct 5, 2014 6:07 PM, Seymore4Head wrote: For the record, I don't want a hint. I want the answer. I see a practice question is similar to this. 15 = x 30 And it wants a similar expression that is equivalent. Maybe 30 x = 15 ? Seems more similar to the original expression than the other possibilities. As to how to try it out, bring up the Python prompt, assign various values to x, and keep evaluating the possibilities. To simplify evaluation off a bunch of alternatives, consider defining a function which takes x add a parameter and print out the various expression values. I'd give a concrete example, but don't has a prompt available on my phone... An interesting data-point. We have a here a poster who's asked some 20 or so python questions and still seems not to know how to use the interpreter interactively. Sorry Seymore if this sounds condescending -- its not a complaint against you but against those who treat the print statement/expression as kosher for newbies. Imagine someone who has driven a car for a month but has no clue about the basic rule of keep-left (or right). -- https://mail.python.org/mailman/listinfo/python-list
Re: Best Practice Question
- Original Message - [...] By the way, did someone ever notice that r'\' fails ? I'm sure there's a reason for that... (python 2.5) Anyone knows ? r'\' SyntaxError: EOL while scanning single-quoted string Even in a raw string, string quotes can be escaped with a backslash, but the backslash remains in the string; for example, r\ is a valid string literal consisting of two characters: a backslash and a double quote; r\ is not a valid string literal (even a raw string cannot end in an odd number of backslashes). Specifically, a raw string cannot end in a single backslash (since the backslash would escape the following quote character). -- python docs -- http://mail.python.org/mailman/listinfo/python-list Thanks for the pointer. JM -- IMPORTANT NOTICE: The contents of this email and any attachments are confidential and may also be privileged. If you are not the intended recipient, please notify the sender immediately and do not disclose the contents to any other person, use it for any purpose, or store or copy the information in any medium. Thank you. -- http://mail.python.org/mailman/listinfo/python-list
Re: Best Practice Question
On 02/04/2013 11:23 PM, Anthony Correia wrote:
Just started learning Python. I just wrote a simple copy files script. I use
Powershell now as my main scripting language but I wanted to extend into the
linux platform as well. Is this the best way to do it?
import os
objdir = (C:\\temp2)
colDir = os.listdir(objdir)
for f in colDir:
activefile = os.path.join(objdir + \\ + f)
print (Removing + activefile + from + objdir)
os.remove(activefile)
In Powershell I would do this:
$colDir = gci -path c:\temp2
$objDir = C:\temp3
ForEach($file in $colDir){
#.Fullname lists the directory and filename together. No need to do a join
#beforehand.
Copy-item $file.fullname -destination $objDir
}
You started two nearly-identical threads, with nearly the same content.
I won't repeat the comments already posted in the other thread, but
notice that your powershell script copies the file, while your Python
translation deletes the file. Big difference.
Next, you should use raw strings, or at least use the forward slash,
rather than double backslashes in file path literals.
--
DaveA
--
http://mail.python.org/mailman/listinfo/python-list
Re: Best Practice Question
- Original Message -
On 02/04/2013 11:23 PM, Anthony Correia wrote:
Just started learning Python. I just wrote a simple copy files
script. I use Powershell now as my main scripting language but I
wanted to extend into the linux platform as well. Is this the
best way to do it?
import os
objdir = (C:\\temp2)
colDir = os.listdir(objdir)
for f in colDir:
activefile = os.path.join(objdir + \\ + f)
print (Removing + activefile + from + objdir)
os.remove(activefile)
In Powershell I would do this:
$colDir = gci -path c:\temp2
$objDir = C:\temp3
ForEach($file in $colDir){
#.Fullname lists the directory and filename together. No need
to do a join
#beforehand.
Copy-item $file.fullname -destination $objDir
}
You started two nearly-identical threads, with nearly the same
content.
I won't repeat the comments already posted in the other thread, but
notice that your powershell script copies the file, while your Python
translation deletes the file. Big difference.
Next, you should use raw strings, or at least use the forward slash,
rather than double backslashes in file path literals.
--
DaveA
He must have hit the send button too early by mistake.
By the way, did someone ever notice that r'\' fails ? I'm sure there's a reason
for that... (python 2.5) Anyone knows ?
r'\'
SyntaxError: EOL while scanning single-quoted string
r'\b'
'\\b'
JM
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Re: Best Practice Question
[...] By the way, did someone ever notice that r'\' fails ? I'm sure there's a reason for that... (python 2.5) Anyone knows ? r'\' SyntaxError: EOL while scanning single-quoted string Even in a raw string, string quotes can be escaped with a backslash, but the backslash remains in the string; for example, r\ is a valid string literal consisting of two characters: a backslash and a double quote; r\ is not a valid string literal (even a raw string cannot end in an odd number of backslashes). Specifically, a raw string cannot end in a single backslash (since the backslash would escape the following quote character). -- python docs -- http://mail.python.org/mailman/listinfo/python-list
Re: Best Practice Question
On Tue, 5 Feb 2013 15:32:32 +0100 (CET), Jean-Michel Pichavant wrote: By the way, did someone ever notice that r'\' fails ? I'm sure there's a reason for that... (python 2.5) Anyone knows ? r'\' SyntaxError: EOL while scanning single-quoted string I hit this all the time with Vim's path-completion (:help i_CTRL-X_CTRL-F) on Win32 which puts a trailing \ on directory-names. I just need to remember to remove it, a task made easier because the syntax highlighting correctly shows how Python interprets it (i.e., the string is still continued). -tkc -- http://mail.python.org/mailman/listinfo/python-list
Re: Best Practice Question
On Tuesday, February 5, 2013 10:17:54 AM UTC-5, pytho...@tim.thechases.com wrote: On Tue, 5 Feb 2013 15:32:32 +0100 (CET), Jean-Michel Pichavant wrote: By the way, did someone ever notice that r'\' fails ? I'm sure there's a reason for that... (python 2.5) Anyone knows ? r'\' SyntaxError: EOL while scanning single-quoted string I hit this all the time with Vim's path-completion (:help i_CTRL-X_CTRL-F) on Win32 which puts a trailing \ on directory-names. I just need to remember to remove it, a task made easier because the syntax highlighting correctly shows how Python interprets it (i.e., the string is still continued). -tkc Sorry about that I hit the touchpad on my laptop by mistake. Beside the using single '\' vs a double '\\' does that look ok? -- http://mail.python.org/mailman/listinfo/python-list
Re: Best Practice Question
On Tue, Feb 5, 2013 at 11:40 AM, Anthony Correia akcorr...@gmail.comwrote:
On Tuesday, February 5, 2013 10:17:54 AM UTC-5,
pytho...@tim.thechases.comwrote:
On Tue, 5 Feb 2013 15:32:32 +0100 (CET), Jean-Michel Pichavant wrote:
By the way, did someone ever notice that r'\' fails ? I'm sure
there's a reason for that... (python 2.5) Anyone knows ?
r'\'
SyntaxError: EOL while scanning single-quoted string
I hit this all the time with Vim's path-completion (:help
i_CTRL-X_CTRL-F) on Win32 which puts a trailing \ on
directory-names. I just need to remember to remove it, a task made
easier because the syntax highlighting correctly shows how Python
interprets it (i.e., the string is still continued).
-tkc
Sorry about that I hit the touchpad on my laptop by mistake. Beside the
using single '\' vs a double '\\' does that look ok?
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according to the docs for os.path.join, you don't need the backslash stuff
at all. Python knows the correct separator for your os and inserts it
accordingling:
I'm on linux:
import os
p = os.path.join('bob', 'bill')
p
'bob/bill'
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Joel Goldstick
http://joelgoldstick.com
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Re: Best Practice Question
On 02/05/2013 11:53 AM, Joel Goldstick wrote:
On Tue, Feb 5, 2013 at 11:40 AM, Anthony Correia akcorr...@gmail.comwrote:
On Tuesday, February 5, 2013 10:17:54 AM UTC-5, pytho...@tim.thechases.comwrote:
On Tue, 5 Feb 2013 15:32:32 +0100 (CET), Jean-Michel Pichavant wrote:
By the way, did someone ever notice that r'\' fails ? I'm sure
there's a reason for that... (python 2.5) Anyone knows ?
r'\'
SyntaxError: EOL while scanning single-quoted string
I hit this all the time with Vim's path-completion (:help
i_CTRL-X_CTRL-F) on Win32 which puts a trailing \ on
directory-names. I just need to remember to remove it, a task made
easier because the syntax highlighting correctly shows how Python
interprets it (i.e., the string is still continued).
-tkc
Sorry about that I hit the touchpad on my laptop by mistake. Beside the
using single '\' vs a double '\\' does that look ok?
--
http://mail.python.org/mailman/listinfo/python-list
according to the docs for os.path.join, you don't need the backslash stuff
at all. Python knows the correct separator for your os and inserts it
accordingling:
I'm on linux:
import os
p = os.path.join('bob', 'bill')
p
'bob/bill'
Worse than that, the code as posted by the OP used string concatenation
before calling os.path.join(), and the latter method does nothing at
all, when presented with a single string.
--
DaveA
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Best Practice Question
Just started learning Python. I just wrote a simple copy files script. I use
Powershell now as my main scripting language but I wanted to extend into the
linux platform as well. Is this the best way to do it?
import os
objdir = (C:\\temp2)
colDir = os.listdir(objdir)
for f in colDir:
activefile = os.path.join(objdir + \\ + f)
print (Removing + activefile + from + objdir)
os.remove(activefile)
In Powershell I would do this:
$colDir = gci -path c:\temp2
$objDir = C:\temp3
ForEach($file in $colDir){
#.Fullname lists the directory and filename together. No need to do a join
#beforehand.
Copy-item $file.fullname -destination $objDir
}
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distutils + mercurial good practice question
distutils generates a number of files automatically in my projects, including MANIFEST, build/* and dist/* Is there any reason why I would want or need to track them in mercurial? I currently have this .hgignore file: syntax: glob *.pyc *~ exclude/* build/* dist/* MANIFEST Good practice or bad practice? -- Steven -- http://mail.python.org/mailman/listinfo/python-list
Re: XML-schema 'best practice' question
On Sep 18, 8:28 am, Frank Millman [EMAIL PROTECTED] wrote: Hi all This is not strictly a Python question, but as I am writing in Python, and as I know there are some XML gurus on this list, I hope it is appropriate here. XML-schemas are used to define the structure of an xml document, and to validate that a particular document conforms to the schema. They can also be used to transform the document, by filling in missing attributes with default values. [..] Or maybe the best practice is to *always* validate a document before processing it. I have realised that my question was irrelevant. xml's raison d'etre is to facilitate the exchange of information between separate entities. If I want to use xml as a method of serialisation within my own system, I can do what I like, but there can be no question of 'best practice' in this situation. When xml is used as intended, and you want to process a document received from a third party, there is no doubt that you should always validate it first before processing it. Thank you, Lorenzo, for pointing out the obvious. It may take me a while to catch up, but at least I can see things a little more clearly now. As to why I am using xml at all, I know that there is a serious side to Skip's light-hearted comment, so I will try to explain. I want to introduce an element of workflow management (aka Business Process Management) into the business/accounting system I am developing. I used google to try to find out what the current state of the art is. After several months of very confusing research, this is the present situation, as best as I can figure it out. There is an OMG spec called BPMN, for Business Process Modeling Notation. It provides a graphical notation, intended to be readily understandable by all business users, from business analysts, to technical developers, to those responsible for actually managing and monitoring the processes. Powerful though it is, it does not provide a standard method of serialsing the diagram, so there is no standard way of exchanging a diagram between different vendors, or of using it as input to a workflow engine. There is an OASIS spec called WS-BPEL, for Web Services Business Process Execution Language. It defines a language for specifying business process behavior based on Web Services. This does have a formal xml-based specification. However, it only covers processes invoked via web services - it does not cover workflow-type processes within an organisation. To try to fill this gap, a few vendors got together and submitted a draft specification called BPEL4People. This proposes a series of extensions to the WS-BPEL spec. It is still at the evaluation stage. The BPMN spec includes a section which attempts to provide a mapping between BPMN and BPEL, but the authors state that there are areas of incompatibility, so it is not a perfect mapping. Eventually I would like to make sense of all this, but for now I want to focus on BPMN, and ignore BPEL. I can use wxPython to design a BPMN diagram, but I have to invent my own method of serialising it so that I can use it to drive the business process. For good or ill, I decided to use xml, as it seems to offer the best chance of keeping up with the various specifications as they evolve. I don't know if this is of any interest to anyone, but it was therapeutic for me to try to organise my thoughts and get them down on paper. I am not expecting any comments, but if anyone has any thoughts to toss in, I will read them with interest. Thanks Frank -- http://mail.python.org/mailman/listinfo/python-list
Re: XML-schema 'best practice' question
On 20 Set, 07:59, Frank Millman [EMAIL PROTECTED] wrote: I want to introduce an element of workflow management (aka Business Process Management) into the business/accounting system I am developing. I used google to try to find out what the current state of the art is. After several months of very confusing research, this is the present situation, as best as I can figure it out. What is the state of the art of existing, working software? Can you leverage it instead of starting from scratch? For example, the existing functionality of your accounting software can be reorganized as a suite of components, web services etc. that can be embedded in workflow definitions, and/or executing a workflow engine can become a command in your application. There is an OMG spec called BPMN, for Business Process Modeling Notation. It provides a graphical notation [snip] there is no standard way of exchanging a diagram between different vendors, or of using it as input to a workflow engine. So BPMN is mere theory. This spec might be a reference for evaluating actual systems, but not a standard itself. There is an OASIS spec called WS-BPEL, for Web Services Business Process Execution Language. It defines a language for specifying business process behavior based on Web Services. This does have a formal xml-based specification. However, it only covers processes invoked via web services - it does not cover workflow-type processes within an organisation. To try to fill this gap, a few vendors got together and submitted a draft specification called BPEL4People. This proposes a series of extensions to the WS-BPEL spec. It is still at the evaluation stage. Some customers pay good money for buzzword compliance, but are you sure you want to be so bleeding edge that you care not only for WS- something specifications, but for evaluation stage ones? There is no need to wait for BPEL4People before designing workflow systems with human editing, approval, etc. Try looking into case studies of how BPEL is actually used in practice. The BPMN spec includes a section which attempts to provide a mapping between BPMN and BPEL, but the authors state that there are areas of incompatibility, so it is not a perfect mapping. Don't worry, BPMN does not exist: there is no incompatibility. On the other hand, comparing and understanding BPMN and BPEL might reveal different purposes and weaknesses between the two systems and help you distinguish what you need, what would be cool and what is only a bad idea or a speculation. Eventually I would like to make sense of all this, but for now I want to focus on BPMN, and ignore BPEL. I can use wxPython to design a BPMN diagram, but I have to invent my own method of serialising it so that I can use it to drive the business process. For good or ill, I decided to use xml, as it seems to offer the best chance of keeping up with the various specifications as they evolve. If you mean to use workflow architectures to add value to your business and accounting software, your priority should be executing workflows, not editing workflow diagrams (which are a useful but unnecessary user interface layer over the actual workflow engine); making your diagrams and definitions compliant with volatile and unproven specifications should come a distant last. I don't know if this is of any interest to anyone, but it was therapeutic for me to try to organise my thoughts and get them down on paper. I am not expecting any comments, but if anyone has any thoughts to toss in, I will read them with interest. 1) There are a number of open-source or affordable workflow engines, mostly BPEL-compliant and written in Java; they should be more useful than reinventing the wheel. 2) With a good XML editor you can produce the workflow definitions, BPEL or otherwise, that your workflow engine needs, and leave the interactive diagram editor for a phase 2 that might not necessarily come; text editing might be convenient enough for your users, and for graphical output something simpler than an editor (e.g a Graphviz exporter) might be enough. 3) Maybe workflow processing can grow inside your existing accounting application without the sort of big bang redesign you seem to be planning; chances are that the needed objects are already in place and you only need to make workflow more explicit and add appropriate new features. Regards, Lorenzo Gatti -- http://mail.python.org/mailman/listinfo/python-list
Re: XML-schema 'best practice' question
Sorry for pressing the send button too fast. On 20 Set, 07:59, Frank Millman [EMAIL PROTECTED] wrote: I want to introduce an element of workflow management (aka Business Process Management) into the business/accounting system I am developing. I used google to try to find out what the current state of the art is. After several months of very confusing research, this is the present situation, as best as I can figure it out. What is the state of the art of existing, working software? Can you leverage it instead of starting from scratch? For example, the existing functionality of your accounting software can be reorganized as a suite of components, web services etc. that can be embedded in workflow definitions, and/or executing a workflow engine can become a command in your application. There is an OMG spec called BPMN, for Business Process Modeling Notation. It provides a graphical notation [snip] there is no standard way of exchanging a diagram between different vendors, or of using it as input to a workflow engine. So BPMN is mere theory. This spec might be a reference for evaluating actual systems, but not a standard itself. There is an OASIS spec called WS-BPEL, for Web Services Business Process Execution Language. It defines a language for specifying business process behavior based on Web Services. This does have a formal xml-based specification. However, it only covers processes invoked via web services - it does not cover workflow-type processes within an organisation. To try to fill this gap, a few vendors got together and submitted a draft specification called BPEL4People. This proposes a series of extensions to the WS-BPEL spec. It is still at the evaluation stage. Some customers pay good money for buzzword compliance, but are you sure you want to be so bleeding edge that you care not only for WS- something specifications, but for evaluation stage ones? There is no need to wait for BPEL4People before designing workflow systems with human editing, approval, etc. Try looking into case studies of how BPEL is actually used in practice. The BPMN spec includes a section which attempts to provide a mapping between BPMN and BPEL, but the authors state that there are areas of incompatibility, so it is not a perfect mapping. Don't worry, BPMN does not exist: there is no incompatibility. On the other hand, comparing and understanding BPMN and BPEL might reveal different purposes and weaknesses between the two systems and help you distinguish what you need, what would be cool and what is only a bad idea or a speculation. Eventually I would like to make sense of all this, but for now I want to focus on BPMN, and ignore BPEL. I can use wxPython to design a BPMN diagram, but I have to invent my own method of serialising it so that I can use it to drive the business process. For good or ill, I decided to use xml, as it seems to offer the best chance of keeping up with the various specifications as they evolve. If you mean to use workflow architectures to add value to your business and accounting software, your priority should be executing workflows, not editing workflow diagrams (which are a useful but unnecessary user interface layer over the actual workflow engine); making your diagrams and definitions compliant with volatile and unproven specifications should come a distant last. I don't know if this is of any interest to anyone, but it was therapeutic for me to try to organise my thoughts and get them down on paper. I am not expecting any comments, but if anyone has any thoughts to toss in, I will read them with interest. 1) There are a number of open-source or affordable workflow engines, mostly BPEL-compliant and written in Java; they should be more useful than reinventing the wheel. 2) With a good XML editor you can produce the workflow definitions, BPEL or otherwise, that your workflow engine needs, and leave the interactive diagram editor for a phase 2 that might not necessarily come; text editing might be convenient enough for your users, and for graphical output something simpler than an editor (e.g a Graphviz exporter) might be enough. 3) Maybe workflow processing can grow inside your existing accounting application without the sort of big bang redesign you seem to be planning; chances are that the needed objects are already in place and you only need to make workflow more explicit and add appropriate new features. Regards, Lorenzo Gatti -- http://mail.python.org/mailman/listinfo/python-list
XML-schema 'best practice' question
Hi all This is not strictly a Python question, but as I am writing in Python, and as I know there are some XML gurus on this list, I hope it is appropriate here. XML-schemas are used to define the structure of an xml document, and to validate that a particular document conforms to the schema. They can also be used to transform the document, by filling in missing attributes with default values. In my situation, both the creation and the processing of the xml document are under my control. I know that this begs the question 'why use xml in the first place', but let's not go there for the moment. Using minixsv, validating a document with a schema works, but is quite slow. I appreciate that lxml may be quicker, but I think that my question is still applicable. I am thinking of adding a check to see if a document has changed since it was last validated, and if not, skip the validation step. However, I then do not get the default values filled in. I can think of two possible solutions. I just wondered if this is a common design issue when it comes to xml and schemas, and if there is a 'best practice' to handle it. 1. Don't use default values - create the document with all values filled in. 2. Use python to check for missing values and fill in the defaults when processing the document. Or maybe the best practice is to *always* validate a document before processing it. How do experienced practitioners handle this situation? Thanks for any hints. Frank Millman -- http://mail.python.org/mailman/listinfo/python-list
Re: XML-schema 'best practice' question
On 18 Set, 08:28, Frank Millman [EMAIL PROTECTED] wrote: I am thinking of adding a check to see if a document has changed since it was last validated, and if not, skip the validation step. However, I then do not get the default values filled in. I can think of two possible solutions. I just wondered if this is a common design issue when it comes to xml and schemas, and if there is a 'best practice' to handle it. 1. Don't use default values - create the document with all values filled in. 2. Use python to check for missing values and fill in the defaults when processing the document. Or maybe the best practice is to *always* validate a document before processing it. The stated problem rings a lot of premature optimization bells; performing the validation and default-filling step every time, unconditionally, is certainly the least crooked approach. In case you really want to avoid unnecessary schema processing, if you are willing to use persistent data to check for changes (for example, by comparing a hash or the full text of the current document with the one from the last time you performed validation) you can also store the filled-in document that you computed, either as XML or as serialized Python data structures. Regards, Lorenzo Gatti -- http://mail.python.org/mailman/listinfo/python-list
Re: XML-schema 'best practice' question
Frank 1. Don't use default values - create the document with all values Frank filled in. Frank 2. Use python to check for missing values and fill in the defaults Frank when processing the document. Frank Or maybe the best practice is to *always* validate a document Frank before processing it. Frank How do experienced practitioners handle this situation? 3. Don't use XML. (sorry, couldn't resist) Skip -- http://mail.python.org/mailman/listinfo/python-list
