Re: [Tutor] Alternatives to append() for growing a list
On Sun, Dec 08, 2013 at 04:10:45PM +1000, Amit Saha wrote: It didn't have to do with strings. It was a basic example of using append() which is to start with an empty list and and then build it incrementally: l = [ ] l.append(1) # append more If this is literally what the code does, then it's fat and slow and should be replaced with this: # not this l = [] l.append(1) l.append(2) l.append(x) l.append(y) # this is even worse, despite being shorter l = [] for item in [1, 2, x, y]: l.append(item) # this is the way to do it l = [1, 2, x, y] But without seeing the specific code in question, it is impossible to judge whether you are using append appropriately or not. -- Steven ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor
[Tutor] Suggestion required on python as scripting language
Hi All, I am working as test engineer in Networking in storage domain. We have decided to automate our testing and have chosen python for the same. We have basic knowledge on python so can anyone suggest good tutorials for writing automation scripts using python. Thanks in advance, Shanky ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor
[Tutor] Unit testing in Python (3.3.0) for beginners
Hey there, I struggle to understand what unit testing specifically means in practice and how to actually write unit tests for my code (my gut is telling me that it's a fairly important concept to understand). Over the last few days I learned how to write and work with classes, I learned quite a lot about functions, nested loops and I currently walk through every program in the Python.org wiki Simple Programs https://wiki.python.org/moin/SimplePrograms ... and here's the unit test program they provide: import unittest def median(pool): copy = sorted(pool) size = len(copy) if size % 2 == 1: return copy[(size - 1) / 2] else: return (copy[size/2 - 1] + copy[size/2]) / 2 class TestMedian(unittest.TestCase): def testMedian(self): self.failUnlessEqual(median([2, 9, 9, 7, 9, 2, 4, 5, 8]), 7) if __name__ == '__main__': unittest.main() Also, I went through the Beginning Test-Driven Development in Python http://net.tutsplus.com/tutorials/python-tutorials/test-driven-development-in-python/ but I have to admit I still don't fully understand how unit tests work in practice and how to write my own unit tests. As it turned out over the last few weeks, the best modus operandi for me as an absolute beginner is to grab a small program, take it apart in the first place, understand how each component works through trial error, then put all those pieces together and then I kind of get the big picture. Once I get it I practice as much as possible to memorize what I just learned and *then* I start readying as many blogs, tutorials etc. as possible to deepen my understanding (I frankly find most tutorials blogs too complex and confusing from a beginner's viewpoint, and I learn faster by taking code apart and learning through trial error in the first place). So, what I am specifically searching for is a very simple code sample which I can take apart and iterate through each component, and I was wondering if you are aware of resources that might be helpful? My understanding of unit testing is that I have to embed my code into a test and then I have to define conditions under which my code is supposed to fail and pass. Is that assumption correct? I am a bit lost confused here .. any help hing is highly appreciated! Thank you all the best, Raf ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Unit testing in Python (3.3.0) for beginners
On Sun, Dec 8, 2013 at 8:22 PM, Rafael Knuth rafael.kn...@gmail.com wrote: Hey there, I struggle to understand what unit testing specifically means in practice and how to actually write unit tests for my code (my gut is telling me that it's a fairly important concept to understand). Your gut feeling is right. However, you will only *truly* understand it's usefulness as you write more programs yourself. No matter how many articles or blog posts or books you read it in, it's something which you will yourself have to realize and once you do so, you will find great value in it. Also, don't fret if you don't realize it. You will, sooner or latter. Here is a fairly common use case where you will really find tests useful (try it!): Say, you have a fairly big program, single file (module) or spread across multiple files. Now, as you improve your understanding, you realize that you can write more efficient/elegant code. So you go on a wholesale refactoring spree (the technical term for changing your existing code to cleanup your existing code to write more optimized or idiomatic code). However, you are not very confident that all the changes haven't broken any of your existing features. So, what do you do? When you don't have tests, you have to manually imagine and run the programs for all possible inputs and check if the output/results are as expected. On the other hand, if you have a tests, you can simply run these tests and refactor your code confidently. However, I have also realized during my own learning adventures and learning from the existing code base and users' bug reports that the benefit of tests are solely dependent on the the test cases you have covered in your tests. If you missed a scenario (a test case) in your tests, then it is likely that any breakage of functionality in that area of your program will not be undetected when you run the tests. Over the last few days I learned how to write and work with classes, I learned quite a lot about functions, nested loops and I currently walk through every program in the Python.org wiki Simple Programs https://wiki.python.org/moin/SimplePrograms ... and here's the unit test program they provide: import unittest def median(pool): copy = sorted(pool) size = len(copy) if size % 2 == 1: return copy[(size - 1) / 2] else: return (copy[size/2 - 1] + copy[size/2]) / 2 BTW, this program will not work in Python 3, since a division operation returns a float. so, 4/2 = 2.0 . class TestMedian(unittest.TestCase): def testMedian(self): self.failUnlessEqual(median([2, 9, 9, 7, 9, 2, 4, 5, 8]), 7) if __name__ == '__main__': unittest.main() Also, I went through the Beginning Test-Driven Development in Python http://net.tutsplus.com/tutorials/python-tutorials/test-driven-development-in-python/ but I have to admit I still don't fully understand how unit tests work in practice and how to write my own unit tests. I will attempt an explanation with a far simpler function: # myarith.py def sum(a,b): return a+b Let's say you have saved this function in a module, myarith.py. Now, how would you really verify if the function actually returns the sum of the numbers passed to it? By calling the function of course. Here is one way: import myarith myarith.sum(1, 2) 3 myarith.sum(1, 5) 6 myarith.sum(-11, -5) -16 test case So, you are confident that your function works as expected. Now, instead of calling your function as above, you want to use the unittest module. Here is a test module which tests the above function: # test_arith.py import unittest import myarith class ArithTest(unittest.TestCase): def test_sum(self): self.assertEqual(myarith.sum(1,2), 1+2) if __name__ == '__main__': unittest.main() We first create a class ArithTest which is a subclass of unittest.TestCase. This means that, the class ArithTest is a test case and in it you will have various tests to test the functions in your myarith module. Right now, there is only one function, sum(). So, we create a function, test_sum() where we call the sum() function as above, but we call it inside the assertEqual() method which basically tests whether the first argument's value is equal to the second argument. Now, when you run this module, you will see something like: $ python3 test_arith.py . -- Ran 1 test in 0.000s OK Now, let us modify the test_sum() method: import unittest import myarith class ArithTest(unittest.TestCase): def test_sum(self): self.assertEqual(myarith.sum(1,2), 1+2) def test_sum_2(self): self.assertEqual(myarith.sum(2,2), 15) if __name__ == '__main__': unittest.main() A new test has been added, test_sum_2() which is obviously going to fail. Let's see what happens when we run the module again: .F == FAIL: test_sum_2
Re: [Tutor] Unit testing in Python (3.3.0) for beginners
On 12/08/2013 11:22 AM, Rafael Knuth wrote: Hey there, I struggle to understand what unit testing specifically means in practice and how to actually write unit tests for my code (my gut is telling me that it's a fairly important concept to understand). [...] Hello Rafael, This post is quite long, and partly personal. As you guess, testing is in fact an important topic, and there is much to say about it. As usual in programming, the domain comes with its load of ambiguity, contradictions and misunderstandings. Question number 0: why testing? My view is that testing is a tool that helps one making good software by finding bugs, or trying to. There are at least 2 interpretations of this: 1. Help finding symptoms (signs) of errors, meaning obviously wrong things: I will this a control test 2. Help finding the source of such symtoms, meaning the actual error: I call this a diagnosis test. What a test has _not_ as purpose is proving your software correct; this is not possible (except if it is very simple and runs on a closed set of variable input data). Unit testing means testing a whole, consistent section of source code: typically a function, a complex object, a data structtre, or a(nother) class. A test is then one or more test functions that try and find bugs in this section of code. In languages like Python with a prominent concept of module, there can be a module's whole test function, which usually just calls every test func in the module. This may look like this: def test1 (): ... def test2 (): ... def test3 (): ... def test (): test1() test2() test3() if __name__ == __main__: test() # to comment out when running without test pass Now, what does each test func do? Since you just discovered classes, I will use as example a simple Class 'Position' (or part of it): class Position: def __init__ (self, x=0, y=0): self.x, self.y = x, y def move (self, dt): # dt is delta-time (difference of time) Move changes the position according to elapsed time and a movement scheme, maybe as complicated as linear in time (I'm joking); maybe when reaching a border (eg screen limit), an object bounces or magically jumps to the other side; or maybe position also holds vx vy speed coordinates (velocity vector), which also change. To test move, one would provide a series of test data, here a list of dt values. Then create a specimen of Position, run move for each dt, and for each case _check_ that the resulting position is ok. # a series of checks like: pos.move(dt) ok = (pos.x == correct_x) and (pos.y == correct_y) if ok: ... else: ... You may simplify by providing a Position '==' method (__eq__) def __eq__ (self, other) return (self.x == other.x) and (self.y == other.y) # or just tuple equality: return (self.x, self.y) == (other.x, other .y) Which permits checking more simply: # a series of checks like: pos.move(dt) if (pos == correct_pos): ... else: ... Now consider a situation where instead of move we have: def movement (dt): ... return (dx, dy) 'move' was an action-function some performs an effect, thus one checks its effect. 'movement' is an evaluation function, a function properly speaking that computes some value (here, a pair of values), thus we can directly check its output result: # a series of checks like: if pos.movement(dt) == correct_movement: # a tuple (dx, dy): ... else: ... As _simple_ as that. And tests should definitely be simple, stupid. Otherwise we would have to test tests (it happened to me ;-). There are several sources of error in tests: base objects (here a position), test data (dt values), test correct results (new positions), etc... plus test logic if you don't make it trivial enough. A wrong test finds false positives, meaning wrong errors where there are none, and false negatives, meaning good outcomes which actually are bad. One may spoil tons of time because of that... (this also happened to me, in fact numerous times). Tests must be very simple. Another question is: what to check? As you probably guess, all kinds of special values, border values, exceptional values, are the ones to test in priority. In our case, dt=0, dt=1, dt=big, dt=very_very_big. But there is a whole category of checks often completely forgotten, namely failure checks: most methods should just fail on wrong or dubious input (which I call anomalies). What happens if dt is negative? What if it is is an int instead of a float, or conversely (python would happily compute if you don't mind)? What if it's not anumber at all? To test that, if failure of a given function translates to raising an exception (stop program execution with an error message), your check must catch the possible exception. (Maybe you don't know that yet.) And most importantly,
Re: [Tutor] Suggestion required on python as scripting language
On 12/08/2013 07:59 AM, Shankar Donepudi wrote: Hi All, I am working as test engineer in Networking in storage domain. We have decided to automate our testing and have chosen python for the same. We have basic knowledge on python so can anyone suggest good tutorials for writing automation scripts using python. As far as I know, there is no specific Python tutorial for writing automation scripts! This would be surprising, wouldn't it be? (For the record, automation used to be my job domain.) I would just recommend to: * first look at the documentation page on the python.org site * follow one or more of advanced tutorials or guides on python one can find online * search for testing in python and explore what you find, as a source of inspiration (If you you find particularly good and interesting things, maybe bring back information here on this mailing list, so that it can serve others.) Denis ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Alternatives to append() for growing a list
On 12/08/2013 07:14 AM, Amit Saha wrote: If all of the bitN are strings: bit1 + bit2 + bit3 + bit4 + bit5 actually constructs: bit1+bit2 bit1+bit2+bit3 bit1+bit2+bit3+bit4 bit1+bit2+bit3+bit4+bit5 A number of unneeded string object, and a very big useless memory weight. Thanks Denis, good to know this is how it is done. I hadn't thought about it simply because, never have probably concatenated strings beyond the simple adding a new line to a string. This is only due to catenation being defined in python as a _binary_ operation. In principle, there is no reason for this. In a hypothetical language (I will here use Lisp-like syntax just to make a visual difference), one may write: (cat bit1 bit2 bit3 bit4 bit5) Then cat would catenate all bits in one go, into a sigle total string (sum the sizes and make a single whole string of this size). As a side-note, this is also true for common arthmetic operators like + or *, which are not conceptually binary, but we have this impression *due to infix notation*: 1 + 2 + 3 + 4 + 5 is usually interpreted as a series of binary operations: 1 + 2) + 3) + 4) + 5) but there could well be (and in some languages this is the case): (+ 1 2 3 4 5) in one go (even if behind the stage there are binary ops, just because the machine also knows that). Think at manual sum for illustration: 123 456 789 --- result Maybe infix notation is just wrong for some operations and misleads into wrong thinking. We should reserve for actual binary ops, namely - and /; but prefix notation, as illustrated above, would nicely do the job for binary pos as well. (The same point applies to logical operators or and, which are not binary, while the case of relational ones [comparisons] is more obscure.) However, unlike the case of catenation, unjustified binary arithmetic operations do not cause any other harm than needlessly multiplying function or method lookups calls (if there is a call, which is the case in python because such operators can be overloaded). Denis ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Unit testing in Python (3.3.0) for beginners
On 08/12/2013 10:22, Rafael Knuth wrote: Hey there, I struggle to understand what unit testing specifically means in practice and how to actually write unit tests for my code (my gut is telling me that it's a fairly important concept to understand). Over the last few days I learned how to write and work with classes, I learned quite a lot about functions, nested loops and I currently walk through every program in the Python.org wiki Simple Programs https://wiki.python.org/moin/SimplePrograms ... and here's the unit test program they provide: import unittest def median(pool): copy = sorted(pool) size = len(copy) if size % 2 == 1: return copy[(size - 1) / 2] else: return (copy[size/2 - 1] + copy[size/2]) / 2 class TestMedian(unittest.TestCase): def testMedian(self): self.failUnlessEqual(median([2, 9, 9, 7, 9, 2, 4, 5, 8]), 7) if __name__ == '__main__': unittest.main() Also, I went through the Beginning Test-Driven Development in Python http://net.tutsplus.com/tutorials/python-tutorials/test-driven-development-in-python/ but I have to admit I still don't fully understand how unit tests work in practice and how to write my own unit tests. As it turned out over the last few weeks, the best modus operandi for me as an absolute beginner is to grab a small program, take it apart in the first place, understand how each component works through trial error, then put all those pieces together and then I kind of get the big picture. Once I get it I practice as much as possible to memorize what I just learned and *then* I start readying as many blogs, tutorials etc. as possible to deepen my understanding (I frankly find most tutorials blogs too complex and confusing from a beginner's viewpoint, and I learn faster by taking code apart and learning through trial error in the first place). So, what I am specifically searching for is a very simple code sample which I can take apart and iterate through each component, and I was wondering if you are aware of resources that might be helpful? My understanding of unit testing is that I have to embed my code into a test and then I have to define conditions under which my code is supposed to fail and pass. Is that assumption correct? I am a bit lost confused here .. any help hing is highly appreciated! Thank you all the best, Raf Two pieces of advice from me, one don't overthink it, two why not look at Python's own unit tests? On my Windows 7 box they're here C:\Python33\Lib\test, I'm sure you can find the equivalent on your own machine. Perhaps pick some builtin functions and modules from the standard library that you've used, and see how the core developers go about testing them. -- My fellow Pythonistas, ask not what our language can do for you, ask what you can do for our language. Mark Lawrence ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Unit testing in Python (3.3.0) for beginners
On Sun, Dec 08, 2013 at 11:22:37AM +0100, Rafael Knuth wrote: Hey there, I struggle to understand what unit testing specifically means in practice and how to actually write unit tests for my code (my gut is telling me that it's a fairly important concept to understand). In practice, unit testing is a way to check that your code does what you expect it should do. For every function and method (or at least, as many of them as you can), you should test that it does what you expect. What you expect means the following: - when given good input, does the function return the correct result? - when given bad input, does the function fail the way it is supposed to fail? (e.g. raise an exception, return an error code). Also, the unit test module is good for writing regression tests. Every time you discover a bug in your code, before you fix the bug, you should write a test that demonstrates the existence of that bug. Then, if later changes to your program bring the bug back (this is called a regression), the test will fail and you will discover the regression straight away. A simple example: suppose you have a method, Dog.bark(n) which is supposed to return bark! repeated some number of times, and if n is zero or negative it should return the empty string. Normally I put my unit tests in a separate file. So here's some unit tests for the Dog.bark method: import unittest from myprogram import Dog class DogTest(unittest.TestCase): def test_bark_with_positive_argument(self): dog = Dog() self.assertEqual(dog.bark(1), bark!) self.assertEqual(dog.bark(2), bark! bark!) self.assertEqual(dog.bark(5), bark! bark! bark! bark! bark!) def test_bark_with_zero_argument(self): dog = Dog() self.assertEqual(dog.bark(0), ) def test_bark_with_negative_argument(self): dog = Dog() for i in (-1, -2, -3): self.assertEqual(dog.bark(i), ) def test_walk(self): # test the walk method # and so on if __name__ == '__main__': # Only run this part when running this file as a script. unittest.main() (Alas, good tests often end up with tediously long names. Fortunately you don't have to read the test names very often.) The tests all pass! Looks good. But here we see the problem with testing: tests can only show the existence of bugs, they cannot prove that there are no bugs at all. Oh well. At some point, some poor unlucky fellow discovers a bug in the Dog class, and reports it to you: Problem: Dog.bark() returns wrong result dog = Dog() dog.bark(-17) Expected result: Actual result: meow! A fact of life -- you can never (well, hardly ever) test *every* possible result from your functions. Occasionally there will be surprises like this. Nevermind, this is the job of the program: fix the bugs as they are discovered. So we add an extra test to the unit tests. This one is going to test for regressions, so we don't just modify the existing negative argument test, but we make sure this is a specific, individual test. class DogTest(unittest.TestCase): [...other methods remain the same] def test_bark_with_negative_argument(self): dog = Dog() samples = [1, 2, 3, 4, 5] + random.sample(range(6, 1), 20) for i in samples: self.assertEqual(dog.bark(-i), ) def test_regression_bug_id_92(self): dog = Dog() self.assertEqual(dog.bark(-17), ) Notice that I've made the negative_argument case a lot more vigorous at testing the method. It's a matter of personal judgement how many cases you should check, but given that we've missed one bug, that's a good sign that we didn't check enough. So now instead of testing just a small handful, I test the first five negative values plus another 20 randomly choosen ones. I also add a specific regression test to ensure that this bug can never happen again. In this example I've put the Bug Report ID in the test name, but that's not compulsary. The important thing is that you have a test for the bug. If I run the DogTest now, test_regression_bug_id_92 fails, because I haven't fixed the bug. This proves that the test works as expected. Now I fix the bug, re-run the DogTest, and hopefully everything passes. If so, I can be reasonably sure that there are no obvious bugs in the parts of the code I've actually tested. [...] Also, I went through the Beginning Test-Driven Development in Python http://net.tutsplus.com/tutorials/python-tutorials/test-driven-development-in-python/ but I have to admit I still don't fully understand how unit tests work in practice and how to write my own unit tests. How unit tests work -- the unittest module is a big, complicated package that defines a whole lot of classes and methods. The idea is that the module defines a class that understands how to perform testing. It knows how to run assertSomething methods, or if you prefer,
Re: [Tutor] Unit testing in Python (3.3.0) for beginners
On 08/12/13 10:22, Rafael Knuth wrote: My understanding of unit testing is that I have to embed my code into a test and then I have to define conditions under which my code is supposed to fail and pass. Is that assumption correct? That's correct for any kind of unit testing, not just using the unittest module. Others have shown how to get started with it. Here are some things to think about when testing. If you have input parameters that are collections, say a list, then always test how the function reacts to an empty list, or a different type of collection, say a tuple, or a list of data other than the expected type (say you expect a list of numbers and get strings instead). And a very large list(some function use recursion which can break with large data sets) In other words think of what somebody else using your function might to do it that could break it. Similarly with numbers that, say, act as indexes into a list. Check for negative numbers, zero, small positive numbers, large numbers, floats, non-numbers Hopefully that gives some idea of the kinds of things you should test for. In a real-world project the test code is often bigger (sometime much bigger) than the code being tested (although also much more repetitive!). -- Alan G Author of the Learn to Program web site http://www.alan-g.me.uk/ http://www.flickr.com/photos/alangauldphotos ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Suggestion required on python as scripting language
On 12/8/2013 1:59 AM, Shankar Donepudi wrote: Hi All, I am working as test engineer in Networking in storage domain. We have decided to automate our testing and have chosen python for the same. We have basic knowledge on python so can anyone suggest good tutorials for writing automation scripts using python. It might help if you were more specific. What are you testing? What in your domain does an automation script do? ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Suggestion required on python as scripting language
Hello, On Sun, Dec 8, 2013 at 4:59 PM, Shankar Donepudi umasankar.donep...@gmail.com wrote: Hi All, I am working as test engineer in Networking in storage domain. We have decided to automate our testing and have chosen python for the same. We have basic knowledge on python so can anyone suggest good tutorials for writing automation scripts using python. As others have mentioned, you will most need to be more specific about what you are trying to do and any specific problems you are facing. I am going to take a guess and perhaps a book such Python for Unix and Linux System Administration [1] may give you some ideas. I also wrote this article a while ago [2] which is a fairly basic introduction/treatment of exploring Linux using Python. [1] http://shop.oreilly.com/product/9780596515829.do (The reviews aren't so good, but I did go through it and you will likely find useful things there) [2] http://amitsaha.github.io/site/notes/articles/python_linux/article.html Best, Amit. -- http://echorand.me ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor
[Tutor] saving Tkinter canvas as jpg
Hello. I'm writing a program to draw pictures. I'm using Python 2.7.3 on Mac OSx. I'm trying to find a good way to save the canvas as a jpg (or other pic formats). The advice I've found on stackoverflow is ImageGrab from PIL, but apparently that doesn't work for macs. I get the no module named _grabscreen ImportError. Can you recommend a good module for saving the canvas into a picture file? Thank you, Ben ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] saving Tkinter canvas as jpg
On Sun, Dec 8, 2013 at 7:14 PM, Benjamin Fishbein bfishbei...@gmail.comwrote: Hello. I'm writing a program to draw pictures. I'm using Python 2.7.3 on Mac OSx. I'm trying to find a good way to save the canvas as a jpg (or other pic formats). The advice I've found on stackoverflow is ImageGrab from PIL, but apparently that doesn't work for macs. I get the no module named _grabscreen ImportError. Can you recommend a good module for saving the canvas into a picture file? Thank you, Ben ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor Have you imported PIL ? Show a small coding example here with the traceback. Cut and paste the traceback, don't paraphrase it. -- Joel Goldstick http://joelgoldstick.com ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor
[Tutor] No module named '_tkinter'
Hi, I'm running Ubuntu 10.04 and I've installed python 3.3.3 from the tarball at http://python.org/ftp/python/3.3.3/Python-3.3.3.tar.xz Here is the error I get when trying to run tkinter. pierre@Sprint:~$ python3.3 Python 3.3.3 (default, Dec 2 2013, 11:10:53) [GCC 4.6.3] on linux Type help, copyright, credits or license for more information. import tkinter Traceback (most recent call last): File stdin, line 1, in module File /usr/local/lib/python3.3/tkinter/__init__.py, line 40, in module import _tkinter # If this fails your Python may not be configured for Tk ImportError: No module named '_tkinter' I've tried installing python3-tk from the Ubuntu repository but it doesn't help. Any suggestion on how to install the tkinter module with this version? Thank you, PierreD. ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] saving Tkinter canvas as jpg
Have you imported PIL ? Show a small coding example here with the traceback. Cut and paste the traceback, don't paraphrase it. Here's what printed out: Traceback (most recent call last): File pyshell#65, line 1, in module from PIL import ImageGrab File /Library/Python/2.7/site-packages/PIL/ImageGrab.py, line 34, in module import _grabscreen ImportError: No module named _grabscreen From what I've seen online, this isn't available for mac...of course everything about this module is several years old, and it hasn't been updated with a new version in a few years, so I think there must be something better than it. I'm writing a program to draw pictures. I'm using Python 2.7.3 on Mac OSx. I'm trying to find a good way to save the canvas as a jpg (or other pic formats). The advice I've found on stackoverflow is ImageGrab from PIL, but apparently that doesn't work for macs. I get the no module named _grabscreen ImportError. Can you recommend a good module for saving the canvas into a picture file? Thank you, Ben -- Joel Goldstick http://joelgoldstick.com ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] saving Tkinter canvas as jpg
On Sun, Dec 8, 2013 at 8:10 PM, Benjamin Fishbein bfishbei...@gmail.comwrote: Have you imported PIL ? Show a small coding example here with the traceback. Cut and paste the traceback, don't paraphrase it. Here's what printed out: Traceback (most recent call last): File pyshell#65, line 1, in module from PIL import ImageGrab File /Library/Python/2.7/site-packages/PIL/ImageGrab.py, line 34, in module import _grabscreen ImportError: No module named _grabscreen What happens if you import PIL like this: import PIL You will then need to use PIL.ImageGrab in your code From what I've seen online, this isn't available for mac...of course everything about this module is several years old, and it hasn't been updated with a new version in a few years, so I think there must be something better than it. I'm writing a program to draw pictures. I'm using Python 2.7.3 on Mac OSx. I'm trying to find a good way to save the canvas as a jpg (or other pic formats). The advice I've found on stackoverflow is ImageGrab from PIL, but apparently that doesn't work for macs. I get the no module named _grabscreen ImportError. Can you recommend a good module for saving the canvas into a picture file? Thank you, Ben -- Joel Goldstick http://joelgoldstick.com -- Joel Goldstick http://joelgoldstick.com ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] saving Tkinter canvas as jpg
From what I've seen online, this isn't available for mac...of course everything about this module is several years old, and it hasn't been updated with a new version in a few years, so I think there must be something better than it. You could give Pillow a try. It is a fork of the PIL library and more up to date. https://pypi.python.org/pypi/Pillow/ Thanks -Srini ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] saving Tkinter canvas as jpg
On 09/12/2013 01:10, Benjamin Fishbein wrote: Here's what printed out: Traceback (most recent call last): File pyshell#65, line 1, in module from PIL import ImageGrab File /Library/Python/2.7/site-packages/PIL/ImageGrab.py, line 34, in module import _grabscreen ImportError: No module named _grabscreen From what I've seen online, this isn't available for mac...of course everything about this module is several years old, and it hasn't been updated with a new version in a few years, so I think there must be something better than it. https://pypi.python.org/pypi/Pillow/ is a fork of PIL. I've never used it myself but here's hoping!!! -- My fellow Pythonistas, ask not what our language can do for you, ask what you can do for our language. Mark Lawrence ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] No module named '_tkinter'
Can you try importing the module '_tkinter' On 09-Dec-2013 6:43 AM, pierre dagenais eq...@ncf.ca wrote: Hi, I'm running Ubuntu 10.04 and I've installed python 3.3.3 from the tarball at http://python.org/ftp/python/3.3.3/Python-3.3.3.tar.xz Here is the error I get when trying to run tkinter. pierre@Sprint:~$ python3.3 Python 3.3.3 (default, Dec 2 2013, 11:10:53) [GCC 4.6.3] on linux Type help, copyright, credits or license for more information. import tkinter Traceback (most recent call last): File stdin, line 1, in module File /usr/local/lib/python3.3/tkinter/__init__.py, line 40, in module import _tkinter # If this fails your Python may not be configured for Tk ImportError: No module named '_tkinter' I've tried installing python3-tk from the Ubuntu repository but it doesn't help. Any suggestion on how to install the tkinter module with this version? Thank you, PierreD. ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] saving Tkinter canvas as jpg
On Sun, Dec 8, 2013 at 8:49 PM, Mark Lawrence breamore...@yahoo.co.uk wrote: https://pypi.python.org/pypi/Pillow/ is a fork of PIL. I've never used it myself but here's hoping!!! ImageGrab has built-in support for Microsoft Windows only: https://github.com/python-imaging/Pillow/blob/2.2.1/PIL/ImageGrab.py#L29 https://github.com/python-imaging/Pillow/blob/2.2.1/_imaging.c#L3365 https://github.com/python-imaging/Pillow/blob/2.2.1/display.c#L313 A Tk canvas supports saving to a PostScript file, if that suffices (i.e. if you can render PostScript as an image): canvas.postscript(file='filename.ps', colormode='color') http://www.tcl.tk/man/tcl8.5/TkCmd/canvas.htm#M51 OS X includes a screencapture utility that you could call with the subprocess module: http://ss64.com/osx/screencapture.html This answer on Stack Overflow uses the OS X CoreGraphics API: http://stackoverflow.com/a/13026264/205580 http://pythonhosted.org/pyobjc/apinotes/Quartz.html Or you could switch to a GUI toolkit with better support for saving images, such as Qt: https://qt-project.org/doc/qt-4.8/qpixmap.html https://qt-project.org/doc/qt-4.8/qpainter.html Here's a really basic example using PyQt4. Clicking on the Capture button paints the widget to a pixmap that's then saved to spam.png and the desktop to screenshot.jpg with 95% quality. import sys from PyQt4 import QtCore, QtGui class Spam(QtGui.QWidget): def __init__(self): super(Spam, self).__init__() self.setGeometry(100, 100, 300, 225) self.setWindowTitle(Spam) self.btncap = QtGui.QPushButton(Capture, self) self.btncap.clicked.connect(self.capture) self.show() def paintEvent(self, event): p = QtGui.QPainter(self) p.setFont(QtGui.QFont(Times, 20)) flags = QtCore.Qt.AlignBottom | QtCore.Qt.AlignRight p.drawText(event.rect(), flags, Spam) def capture(self): wid = app.desktop().winId() QtGui.QPixmap.grabWidget(self).save( spam.png, png) QtGui.QPixmap.grabWindow(wid).save( screenshot.jpg, jpg, 95) if __name__ == __main__: app = QtGui.QApplication(sys.argv) spam = Spam() sys.exit(app.exec_()) ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor
