Re: [Tutor] I can't believe this needs to be this complex
Dick Moores [EMAIL PROTECTED] wrote code I time. What's an example of code that would have System be greater than zero? And what's the distinction between User and System? (I'm using Win XP, if that's relevant.) It may be that XP doesn't report System time. Well, here's one that reads in the text of Dickens' _Little Dorrit_ and returns the word count: IPython CPU timings (estimated): Total runs performed: 10 Times : Total Per run User : 5.94446752311 s, 0.594446752311 s. System:0.0 s,0.0 s. I would definitely have expected some system time there. This one is a Gui that has an Exit button. I called it and then hit the button: IPython CPU timings (estimated): User : 10.5294301371 s. System:0.0 s. That suggests that it is counting elapsed time as user time in which case I'm not sure how it counts system time. It may be an XP issue. Anyone got different results under Linux/MacOS? Alan G. ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] I can't believe this needs to be this complex
At 01:00 AM 8/3/2008, Alan Gauld wrote: Dick Moores [EMAIL PROTECTED] wrote code I time. What's an example of code that would have System be greater than zero? And what's the distinction between User and System? (I'm using Win XP, if that's relevant.) It may be that XP doesn't report System time. Well, here's one that reads in the text of Dickens' _Little Dorrit_ and returns the word count: IPython CPU timings (estimated): Total runs performed: 10 Times : Total Per run User : 5.94446752311 s, 0.594446752311 s. System:0.0 s,0.0 s. I would definitely have expected some system time there. This one is a Gui that has an Exit button. I called it and then hit the button: IPython CPU timings (estimated): User : 10.5294301371 s. System:0.0 s. That suggests that it is counting elapsed time as user time in which case I'm not sure how it counts system time. It may be an XP issue. Anyone got different results under Linux/MacOS? _Little Dorrit_ is available in us-ascii at http://www.gutenberg.org/etext/963; _War and Peace_ at http://www.gutenberg.org/etext/2600. Dick ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] I can't believe this needs to be this complex
On Sun, Aug 3, 2008 at 4:00 AM, Alan Gauld [EMAIL PROTECTED] wrote: Dick Moores [EMAIL PROTECTED] wrote code I time. What's an example of code that would have System be greater than zero? And what's the distinction between User and System? (I'm using Win XP, if that's relevant.) It may be that XP doesn't report System time. From the IPython help for 'run': -t: print timing information at the end of the run. IPython will giveyou an estimated CPU time consumption for your script, which underUnix uses the resource module to avoid the wraparound problems oftime.clock(). Under Unix, an estimate of time spent on system tasksis also given (for Windows platforms this is reported as 0.0). Kent ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] I can't believe this needs to be this complex
At 05:15 AM 8/3/2008, Kent Johnson wrote: On Sun, Aug 3, 2008 at 4:00 AM, Alan Gauld [EMAIL PROTECTED] wrote: Dick Moores [EMAIL PROTECTED] wrote code I time. What's an example of code that would have System be greater than zero? And what's the distinction between User and System? (I'm using Win XP, if that's relevant.) It may be that XP doesn't report System time. From the IPython help for 'run': -t: print timing information at the end of the run. IPython will giveyou an estimated CPU time consumption for your script, which underUnix uses the resource module to avoid the wraparound problems oftime.clock(). Under Unix, an estimate of time spent on system tasksis also given Thanks, Kent. RTFM! (for Windows platforms this is reported as 0.0). I wonder why it is reported for Windows at all? Dick ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] I can't believe this needs to be this complex
At 05:15 AM 8/3/2008, Kent Johnson wrote: On Sun, Aug 3, 2008 at 4:00 AM, Alan Gauld [EMAIL PROTECTED] wrote: Dick Moores [EMAIL PROTECTED] wrote code I time. What's an example of code that would have System be greater than zero? And what's the distinction between User and System? (I'm using Win XP, if that's relevant.) It may be that XP doesn't report System time. From the IPython help for 'run': -t: print timing information at the end of the run. IPython will giveyou an estimated CPU time consumption for your script, which underUnix uses the resource module to avoid the wraparound problems oftime.clock(). Under Unix, an estimate of time spent on system tasksis also given Thanks, Kent. RTFM! (for Windows platforms this is reported as 0.0). I wonder why it is reported for Windows at all? Dick ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
[Tutor] I can't believe this needs to be this complex
I'm pretty new to Python's dictionaries, but I had a need for a function that would find the values in a dict that have more than one key each. It took me several hours to write. See http://py77.python.pastebin.com/f397582d8. Seems to do the job, both with the example shown, and with the dict of colors at http://py77.python.pastebin.com/f796752ff. But I can't believe the function needs to be so complex. And also, I suppose I've reinvented the wheel (again). Please instruct me. My apologies in advance to Kent for not using a single list comprehension. Thanks, Dick Moores ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] I can't believe this needs to be this complex
On Sat, Aug 2, 2008 at 11:07 AM, Dick Moores [EMAIL PROTECTED] wrote: I'm pretty new to Python's dictionaries, but I had a need for a function that would find the values in a dict that have more than one key each. It took me several hours to write. See http://py77.python.pastebin.com/f397582d8. Seems to do the job, both with the example shown, and with the dict of colors at http://py77.python.pastebin.com/f796752ff. But I can't believe the function needs to be so complex. And also, I suppose I've reinvented the wheel (again). Please instruct me. My apologies in advance to Kent for not using a single list comprehension. Well, list comprehension does indeed seem the solution to your problem, although a single list comprehension would not be necessary. I came to http://py77.python.pastebin.com/m4dcbb34f (note: this is untested, I have no Python on the computer I am working on now), or http://py77.python.pastebin.com/f76ba5002 to indeed just use a single list comprehension (or rather, two nested list comprehensions, again untested for the above reason). -- André Engels, [EMAIL PROTECTED] ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] I can't believe this needs to be this complex
At 03:27 AM 8/2/2008, Andre Engels wrote: Content-Transfer-Encoding: base64Content-Disposition: inlineOn Sat, Aug 2, 2008 at 11:07 AM, Dick Moores [EMAIL PROTECTED] wrote: I'm pretty new to Python's dictionaries, but I had a need for a function that would find the values in a dict that have more than one key each. It took me several hours to write. See http://py77.python.pastebin.com/f397582d8ÙY[\ÈÈÈHØÝÚ]Hexample shown, and with the dict of colors at http://py77.python.pastebin.com/f796752ff. [EMAIL PROTECTED] the function needs to be so complex. And also, I suppose I've reinvented the wheel (again). Please instruct me. [EMAIL PROTECTED] list comprehension. Well, list comprehension does indeed seem the solution to your problem, although a single list comprehension would not be necessary. I came to http://py77.python.pastebin.com/m4dcbb34f (note: this is untested, I have no Python on the computer I am working on now), or http://py77.python.pastebin.com/f76ba5002 to indeed just use a single list comprehension (or rather, two nested list comprehensions, again untested for the above reason). You genius! How could you answer so quickly and accurately (20 minutes!) without access to Python? Both of your scripts work, after I corrected one typo. See http://py77.python.pastebin.com/f7b6e51e8. Thanks! Dick Moores ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] I can't believe this needs to be this complex
At 03:49 AM 8/2/2008, Dick Moores wrote: At 03:27 AM 8/2/2008, Andre Engels wrote: Content-Transfer-Encoding: base64Content-Disposition: inlineOn Sat, Aug 2, 2008 at 11:07 AM, Dick Moores [EMAIL PROTECTED] wrote: I'm pretty new to Python's dictionaries, but I had a need for a function that would find the values in a dict that have more than one key each. It took me several hours to write. See http://py77.python.pastebin.com/f397582d8ÙY[\ÈÈÈHØÝÚ]Hexample shown, and with the dict of colors at http://py77.python.pastebin.com/f796752ff. [EMAIL PROTECTED] the function needs to be so complex. And also, I suppose I've reinvented the wheel (again). Please instruct me. [EMAIL PROTECTED] list comprehension. Well, list comprehension does indeed seem the solution to your problem, although a single list comprehension would not be necessary. I came to http://py77.python.pastebin.com/m4dcbb34f (note: this is untested, I have no Python on the computer I am working on now), or http://py77.python.pastebin.com/f76ba5002 to indeed just use a single list comprehension (or rather, two nested list comprehensions, again untested for the above reason). You genius! How could you answer so quickly and accurately (20 minutes!) without access to Python? Both of your scripts work, after I corrected one typo. See http://py77.python.pastebin.com/f7b6e51e8. And here's your one-liner (http://py77.python.pastebin.com/f789096e9) at work on the dict of colors at http://py77.python.pastebin.com/f796752ff. Dick ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] I can't believe this needs to be this complex
On Sat, Aug 2, 2008 at 6:07 AM, Dick Moores [EMAIL PROTECTED] wrote: I'm pretty new to Python's dictionaries, but I had a need for a function that would find the values in a dict that have more than one key each. From your sample output it appears that you want not just the values, but a list of (value, keys) pairs for which there are more than one key. It is easy to just build a reverse dict and filter its items: In [15]: from collections import defaultdict In [16]: rev=defaultdict(list) In [18]: for k, v in d.iteritems(): rev[v].append(k) In [20]: [ [v, keys] for v, keys in rev.iteritems() if len(keys) 1 ] Out[20]: [[1, ['a', 'e', 'g']], [2, ['b', 'f', 'i', 'h']], [4, ['d', 'j']], ['U.S. Senator', ['John McCain', 'Barack Obama']], [56, [45, 55]]] This also has the advantage of making only two passes over the data so its performance should be O(n). Your solution and Andre's make one or more passes over the data for each data element so they will have O(n*n) performance meaning for a large dict they could be very slow. Kent ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] I can't believe this needs to be this complex
At 05:02 AM 8/2/2008, Kent Johnson wrote: On Sat, Aug 2, 2008 at 6:07 AM, Dick Moores [EMAIL PROTECTED] wrote: I'm pretty new to Python's dictionaries, but I had a need for a function that would find the values in a dict that have more than one key each. From your sample output it appears that you want not just the values, but a list of (value, keys) pairs for which there are more than one key. It is easy to just build a reverse dict and filter its items: In [15]: from collections import defaultdict In [16]: rev=defaultdict(list) In [18]: for k, v in d.iteritems(): rev[v].append(k) In [20]: [ [v, keys] for v, keys in rev.iteritems() if len(keys) 1 ] Out[20]: [[1, ['a', 'e', 'g']], [2, ['b', 'f', 'i', 'h']], [4, ['d', 'j']], ['U.S. Senator', ['John McCain', 'Barack Obama']], [56, [45, 55]]] This also has the advantage of making only two passes over the data so its performance should be O(n). Your solution and Andre's make one or more passes over the data for each data element so they will have O(n*n) performance meaning for a large dict they could be very slow. Wow, the genius' genius appears! You're using some Python tools I didn't know about. More study! I made a function of your code and time tested it against mine, using as d that dict of colors at http://py77.python.pastebin.com/f796752ff. Yours is 73 times faster! In [12]: run -t -N10 fcn_values_dupe_keys.py Time was 0.297 seconds Time was 0.328 seconds Time was 0.344 seconds Time was 0.328 seconds Time was 0.313 seconds Time was 0.344 seconds Time was 0.39 seconds Time was 0.297 seconds Time was 0.312 seconds Time was 0.297 seconds IPython CPU timings (estimated): Total runs performed: 10 Times : Total Per run User : 3.3092253345 s, 0.33092253345 s. System:0.0 s,0.0 s. In [13]: run -t -N10 kent1.py Time was 0 seconds Time was 0 seconds Time was 0 seconds Time was 0 seconds Time was 0 seconds Time was 0.015 seconds Time was 0 seconds Time was 0 seconds Time was 0 seconds Time was 0 seconds IPython CPU timings (estimated): Total runs performed: 10 Times : Total Per run User : 0.044969961266 s, 0.0044969961266 s. System:0.0 s,0.0 s. BTW Kent, I'm going to take this opportunity to ask you about System in the IPython timing results. It's always zero for the code I time. What's an example of code that would have System be greater than zero? And what's the distinction between User and System? (I'm using Win XP, if that's relevant.) Thanks, Dick ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] I can't believe this needs to be this complex
At 10:08 AM 8/2/2008, Alan Gauld wrote: Dick Moores [EMAIL PROTECTED] wrote BTW Kent, I'm going to take this opportunity to ask you about System in the IPython timing results. It's always zero for the code I time. What's an example of code that would have System be greater than zero? And what's the distinction between User and System? (I'm using Win XP, if that's relevant.) In timing user time is time that the CPU spends executing user code - your program. System time is time the CPU spends doing OS things. If your code had a blocking call that waited for input on a port say, then the OS might be doing other stuff in the background while your code waited. This would show as system time. In some OR even time spent reading files from disk is counted as system time because your code is executing low level OS functions. Try timing a function that does nothing but read a large file. See if there is any system time showing up. Well, here's one that reads in the text of Dickens' _Little Dorrit_ and returns the word count: In [11]: run -t -N10 timing_test_little_dorrit.py 339832 339832 339832 339832 339832 339832 339832 339832 339832 339832 IPython CPU timings (estimated): Total runs performed: 10 Times : Total Per run User : 5.94446752311 s, 0.594446752311 s. System:0.0 s,0.0 s. Or time a GUI app that waits for user input... This one is a Gui that has an Exit button. I called it and then hit the button: In [4]: run -t ToolkitV15.py IPython CPU timings (estimated): User : 10.5294301371 s. System:0.0 s. So no non-zero System time yet. But thanks for your explanation. Dick ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
