Python for loop parameters

Question

Hi im just wondering what the 4 would do in this code

for y in range(0, height, 4):

Thanks

I suspect the documentation for `range` should explain that. Did you try looking it up? — Mat, Mar 23 '13 at 08:53
The python _documentation_ is available online. Did you try looking it up? — Mat, Mar 23 '13 at 08:54
[Here](http://docs.python.org/2/library/functions.html#range) is the documentation for `range` — Volatility, Mar 23 '13 at 08:54
http://docs.python.org/2/library/functions.html#range. it's the step (optional parameter). you probably should start to use google. — astreal, Mar 23 '13 at 08:55

score 3 · Answer 1 · answered Mar 23 '13 at 08:57

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Range with just one parameter: end.

Range with two parameters: start, end.

Range with three parameters: start, end, step.

So in your specific case

 for y in range(0, height, 4)

0, 4, 8, ..., n, where n < height.

answered Mar 23 '13 at 08:57

Artur K.

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DotPi · Accepted Answer · 2013-03-23T12:44:21.413

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The 4 in the range function used in the for loop indicates the increment step. suppose the value of height is 20. Then the values for y will be set as 0, 0+4=4, 4+4=8, ... till 20 in subsequent iterations of the for loop.

For a more detailed description of range function check out the python documentation at: http://docs.python.org/2/library/functions.html#range

edited Mar 23 '13 at 12:44

answered Mar 23 '13 at 08:56

DotPi

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the 4 is a value in the "range" call - and both are not _part_ of Python's `for` statement - you could clarify that. – jsbueno Mar 23 '13 at 10:56
That is why I had included the python documentation for range. I will edit the answer to reflect it better. – DotPi Mar 23 '13 at 12:43

score 1 · Answer 3 · answered Mar 23 '13 at 09:04

1

plus 4 each time you hit the range. For example,

 for y in range(0, 14, 4)

you will get 0, 4, 8, 12

answered Mar 23 '13 at 09:04

Yarkee

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Python for loop parameters

3 Answers3