Re: best Pythonic way to do this sort: Python newb
Satchidanand Haridas [EMAIL PROTECTED] wrote: So, I want to sort myList by the return of myFunction( value3 ) I tried doing the following... with no luck so far myList.sort(lambda x, y: cmp(myFunction(x[2]), myFunction(y[2])) I think the above statement should be as follows: myList.sort(lambda x, y: cmp(myFunction(x[2]) - myFunction(y[2])) hope that helps. It would help more if you tested it before you posted. cmp takes two arguments (let alone that subtraction may not be defined for the list elements), so the original version is correct. George -- http://mail.python.org/mailman/listinfo/python-list
best Pythonic way to do this sort: Python newb
Hello all I have build a list that contains data in the form below -- simplified for question -- myList = [[value1, value2, value3],[value1, value2, value3], ...] I have a function which takes value3 from the lists above and returns another value. I want to use this returned value to sort the lists. So, my resultant list would be ordered by the return value of the function with value3 as its argument. From a relative Python newb, what is the best way to do this? Thanks for any help offered. -- http://mail.python.org/mailman/listinfo/python-list
Re: best Pythonic way to do this sort: Python newb
Sean Berry [EMAIL PROTECTED] writes: myList = [[value1, value2, value3],[value1, value2, value3], ...] I have a function which takes value3 from the lists above and returns another value. I want to use this returned value to sort the lists. So, my resultant list would be ordered by the return value of the function with value3 as its argument. From a relative Python newb, what is the best way to do this? def get_key(x): return x[2] sorted_list = sorted(myList, key=get_key) -- http://mail.python.org/mailman/listinfo/python-list
Re: best Pythonic way to do this sort: Python newb
Paul Rubin http://[EMAIL PROTECTED] wrote in message news:[EMAIL PROTECTED] Sean Berry [EMAIL PROTECTED] writes: myList = [[value1, value2, value3],[value1, value2, value3], ...] I have a function which takes value3 from the lists above and returns another value. I want to use this returned value to sort the lists. So, my resultant list would be ordered by the return value of the function with value3 as its argument. From a relative Python newb, what is the best way to do this? def get_key(x): return x[2] sorted_list = sorted(myList, key=get_key) Sorry if I am missing something. But. what is sorted here? My simplified function looks like this def myFunction( myNumber ): do some math calculations to myNumber return result of calculations So, I want to sort myList by the return of myFunction( value3 ) I tried doing the following... with no luck so far myList.sort(lambda x, y: cmp(myFunction(x[2]), myFunction(y[2])) Thanks for any help. -- http://mail.python.org/mailman/listinfo/python-list
Re: best Pythonic way to do this sort: Python newb
Satchidanand Haridas (sharidas at zeomega dot com) ZeOmega (www.zeomega.com) Open Minds' Open Solutions Sean Berry wrote: Paul Rubin http://[EMAIL PROTECTED] wrote in message news:[EMAIL PROTECTED] Sean Berry [EMAIL PROTECTED] writes: myList = [[value1, value2, value3],[value1, value2, value3], ...] I have a function which takes value3 from the lists above and returns another value. I want to use this returned value to sort the lists. So, my resultant list would be ordered by the return value of the function with value3 as its argument. From a relative Python newb, what is the best way to do this? def get_key(x): return x[2] sorted_list = sorted(myList, key=get_key) Sorry if I am missing something. But. what is sorted here? My simplified function looks like this def myFunction( myNumber ): do some math calculations to myNumber return result of calculations So, I want to sort myList by the return of myFunction( value3 ) I tried doing the following... with no luck so far myList.sort(lambda x, y: cmp(myFunction(x[2]), myFunction(y[2])) I think the above statement should be as follows: myList.sort(lambda x, y: cmp(myFunction(x[2]) - myFunction(y[2])) hope that helps. regards, Satchit -- http://mail.python.org/mailman/listinfo/python-list
Re: best Pythonic way to do this sort: Python newb
Sean Berry [EMAIL PROTECTED] writes: def get_key(x): return x[2] sorted_list = sorted(myList, key=get_key) Sorry if I am missing something. But. what is sorted here? sorted is a built-in function that sorts the thing that you pass it. It just appeared in Python 2.4, I think. With older versions, yeah, you have to use the .sort method that sorts in place. I tried doing the following... with no luck so far myList.sort(lambda x, y: cmp(myFunction(x[2]), myFunction(y[2])) That looks ok to me. x = [(i,i*i,1 + 17*i**2 - i**3) for i in range(20)] x [(0, 0, 1), (1, 1, 17), (2, 4, 61), (3, 9, 127), (4, 16, 209), (5, 25, 301), (6, 36, 397), (7, 49, 491), (8, 64, 577), (9, 81, 649), (10, 100, 701), (11, 121, 727), (12, 144, 721), (13, 169, 677), (14, 196, 589), (15, 225, 451), (16, 256, 257), (17, 289, 1), (18, 324, -323), (19, 361, -721)] x.sort(lambda a,b:cmp(a[2],b[2])) x [(19, 361, -721), (18, 324, -323), (0, 0, 1), (17, 289, 1), (1, 1, 17), (2, 4, 61), (3, 9, 127), (4, 16, 209), (16, 256, 257), (5, 25, 301), (6, 36, 397), (15, 225, 451), (7, 49, 491), (8, 64, 577), (14, 196, 589), (9, 81, 649), (13, 169, 677), (10, 100, 701), (12, 144, 721), (11, 121, 727)] -- http://mail.python.org/mailman/listinfo/python-list
Re: best Pythonic way to do this sort: Python newb
(sorted is a built-in function in 2.4) def myFunction( data ): Take one of your set of 3, grab [2] (the 3rd) and do calcs, return value do some math calculations to data[2] return result of calculations sorted_list = sorted(myList, key=myFunction) List is sorted in the order of the 'key' values, key being a value returned from myFunction which operates on [2]. -- http://mail.python.org/mailman/listinfo/python-list
