How to write long arithmetic expressions in several lines in python?

Question

I have a long expression, its' not fitting in my screen, I want to write in several lines.

new_matrix[row][element] =  old_matrix[top_i][top_j]+old_matrix[index_i][element]+old_matrix[row][index_j]+old_matrix[row][index_j]

Python gives me 'indent' error if I just break line. Is there way to 'fit' long expression in screen?

See [PEP8](https://www.python.org/dev/peps/pep-0008/#should-a-line-break-before-or-after-a-binary-operator) advice. If you put the expression in `()` then you can break on the operators, e.g. `+` — T Burgis, Dec 04 '18 at 14:50

score 20 · Accepted Answer · answered Dec 04 '18 at 14:55

20

I hate backslashes, so I prefer to enclose the right hand side in parens, and break/indent on the top-level operators:

new_matrix[row][element] = (old_matrix[top_i][top_j]
                            + old_matrix[index_i][element]
                            + old_matrix[row][index_j]
                            + old_matrix[row][index_j])

answered Dec 04 '18 at 14:55

PaulMcG

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this seems the most legit.. i hate slash lines – ERJAN Dec 04 '18 at 15:00

Immijimmi · Answer 2 · 2018-12-04T14:58:16.650

4

You can break expressions into multiple lines by ending each line with \ to indicate the expression will continue on the next line.

Example:

new_matrix[row][element] =  old_matrix[top_i][top_j]+ \
    old_matrix[index_i][element]+old_matrix[row][index_j]+ \
    old_matrix[row][index_j]

edited Dec 04 '18 at 14:58

answered Dec 04 '18 at 14:52

Immijimmi

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3

1

It's not good to continue a line with the same indentation as the start segment. – Psytho Dec 04 '18 at 14:55
Fair point, edited. – Immijimmi Dec 04 '18 at 14:58

score 2 · Answer 3 · answered Dec 04 '18 at 14:50

2

Yes, use \:

new_matrix[row][element] =  old_matrix[top_i][top_j]+old_matrix[index_i]\ 
                            [element]+old_matrix[row][index_j]+old_matrix[row][index_j]

answered Dec 04 '18 at 14:50

yatu

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How to write long arithmetic expressions in several lines in python?

3 Answers3