split the code with big variable names over two lines in python

Question

I want to split python code over two lines, my code is something similar to:

if long_named_three_d_array[first_dimension][second_dimension][third_dimension] == somevalue:
    //dosomething

I want to split above if condition over two lines.

Please help. Thanks.

http://stackoverflow.com/questions/53162/how-can-i-do-a-line-break-line-continuation-in-python — Josh Bleecher Snyder, Apr 10 '12 at 02:28
@JoshBleecherSnyder: I have already looked at it. That does not help. — hrishikeshp19, Apr 10 '12 at 02:30

score 5 · Answer 1 · edited Apr 11 '12 at 00:14

5

In Python, the LHS can be bracketed.

>>> a = {}
>>> a[1] = {}
>>> a[1][2] = {}
>>> (a[1][2]
... [3]) = ''
>>> a
{1: {2: {3: ''}}}
>>> (b) = 2
>>> b
2

This means you can write your line as

if (long_named_three_d_array[first_dimension] 
    [second_dimension]
    [third_dimension] ) == somevalue:
# Rest of code here, obviously properly indented in for the if.

edited Apr 11 '12 at 00:14

Michael Anderson

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answered Apr 10 '12 at 02:27

Ignacio Vazquez-Abrams

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score 1 · Accepted Answer · answered Apr 10 '12 at 02:30

1

You can use the line break continuation character, \.

if long_named_three_d_array[first_dimension] \
    [second_dimension]\
    [third_dimension] == somevalue:
# Rest of code here, obviously properly indented in for the if.

answered Apr 10 '12 at 02:30

Makoto

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thanks, I am looking for somehting similar, but it is not working for me. Can you confirm again. – hrishikeshp19 Apr 10 '12 at 02:33
2

@hrishikeshp19 Make sure you don't have any trailing whitespace after the \ character. – Michael Anderson Apr 10 '12 at 02:34
3

The "trailing slash" line continuation is evil because 1) any whitespace after the slash will break it, as @MichaelAnderson has noted, and also 2) any **comments** after the slash will break it. This is why Python Style Guide, PEP 8, recommends that you don't use the backslash syntax for line continuation. – Li-aung Yip Apr 10 '12 at 02:54
The if expression can be put into brackets instead. Bracketed expressions can be broken into multiple lines without the use of backslashes. – yak Apr 10 '12 at 07:12
@yak: I agree with you and Li-aung Yip. The backslash *is* another way to do it, but bracketing the LHS is the preferred way. – Makoto Apr 10 '12 at 07:22

score 1 · Answer 3 · answered Apr 10 '12 at 02:36

One approach would be to use a temporary variable:

tmp = long_named_three_d_array[first_dimension][second_dimension][third_dimension] 
if tmp == somevalue:
    //dosomething

though shorter, yet descriptive variable identifiers would be a better choice if that's possible.

split the code with big variable names over two lines in python

3 Answers3