General Python Style Question

ewaller · 2014-02-15 01:02:48

Often, I need to make a couple trips through a loop, but do not need to reference to the number of times I have been through the loop. Example:

                for i in range(2):
                    location = self.Move(location,options[direction])

Here, I have an array of directions I can move, and I want to move two spaces an a given direction. To do this, I want to make two moves. I have no need of the index i. Is there a more Pythonic way of doing this where I do not need to declare a variable I never use?

Edit: location is a 2nd order Tuple, options is a Tuple of vectors (2nd order Tuples that are added element by element to location), direction is an integer

Last edited by ewaller (2014-02-15 01:07:39)

progandy · 2014-02-15 01:07:21

Unused variables often get only an underscore as the name. This convention may be used by some python interpreters to improve the execution.

Last edited by progandy (2014-02-15 01:15:13)

ewaller · 2014-02-15 01:10:22

Python 3.3.3 (default, Nov 26 2013, 13:33:18) 
[GCC 4.8.2] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> for _ in range (2): print ("foo")
... 
foo
foo
>>> for _ in range (2): print ("foo"): print (_)
  File "<stdin>", line 1
    for _ in range (2): print ("foo"): print (_)
                                     ^
SyntaxError: invalid syntax
>>>

Interesting. Thank you.

edit:

>>> for _ in range (2): print ("foo") print (_)
  File "<stdin>", line 1
    for _ in range (2): print ("foo") print (_)
                                          ^
SyntaxError: invalid syntax
>>> for _ in range (2): print (_)              
... 
0
1
>>>

Oh, not so interesting, but still interesting

Last edited by ewaller (2014-02-15 01:13:02)

progandy · 2014-02-15 01:15:39

If you want to improve speed, use itertools.repeat(None, times) instead of range(times), it is a bit faster because it doesn't have to generate new python objects but returns the same "None" every time.
Edit: In python2, you have also xrange (return a generator) and range (returns a list). In python3 range was removed and xrange renamed to range.

Last edited by progandy (2014-02-15 01:17:42)

ewaller · 2014-02-15 01:19:47

That is exactly what I was looking for Thanks!

Arch Linux

#1 2014-02-15 01:02:48

General Python Style Question

#2 2014-02-15 01:07:21

Re: General Python Style Question

#3 2014-02-15 01:10:22

Re: General Python Style Question

#4 2014-02-15 01:15:39

Re: General Python Style Question

#5 2014-02-15 01:19:47

Re: General Python Style Question

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