Is it possible to break a long line to multiple lines in Python?

Question

Just like C, you can break a long line into multiple short lines. But in Python, if I do this, there will be an indent error… Is it possible?

Asked By: Bin Chen

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Source

Answer 1

From PEP 8 – Style Guide for Python Code:

The preferred way of wrapping long lines is by using Python’s implied line
continuation inside parentheses, brackets and braces. If necessary, you
can add an extra pair of parentheses around an expression, but sometimes
using a backslash looks better. Make sure to indent the continued line
appropriately.

Example of implicit line continuation:

a = some_function(
    '1' + '2' + '3' - '4')

On the topic of line breaks around a binary operator, it goes on to say:

For decades the recommended style was to break after binary operators.
But this can hurt readability in two ways: the operators tend to get scattered across different columns on the screen, and each operator is moved away from its operand and onto the previous line.

In Python code, it is permissible to break before or after a binary operator, as long as the convention is consistent locally. For new code Knuth’s style (line breaks before the operator) is suggested.

Example of explicit line continuation:

a = '1'   
    + '2' 
    + '3' 
    - '4'

Answered By: Darin Dimitrov

Answer 2

It works in Python too:

>>> 1+
      2+
3
6
>>> (1+
          2+
 3)
6

Answered By: Abyx

Answer 3

As far as I know, it can be done. Python has implicit line continuation (inside parentheses, brackets, and strings) for triple-quoted strings ("""like this""") and the indentation of continuation lines is not important. For more information, you may want to read this article on lexical analysis, from python.org.

Answered By: Michael Foukarakis

Answer 4

There is more than one way to do it.

1). A long statement:

>>> def print_something():
         print 'This is a really long line,', 
               'but we can make it across multiple lines.'

2). Using parenthesis:

>>> def print_something():
        print ('Wow, this also works?',
               'I never knew!')

3). Using again:

>>> x = 10
>>> if x == 10 or x > 0 or 
       x < 100:
       print 'True'

Quoting PEP8:

The preferred way of wrapping long
lines is by using Python’s implied
line continuation inside parentheses, brackets and braces. If necessary,
you can add an extra pair of parentheses around an expression, but
sometimes using a backslash looks better. Make sure to indent the continued line
appropriately. The preferred place to break around a binary
operator is after the operator, not before it.

Answered By: user225312

Answer 5

If you want to assign a long string to variable, you can do it as below:

net_weights_pathname = (
    '/home/acgtyrant/BigDatas/'
    'model_configs/lenet_iter_10000.caffemodel')

Do not add any comma, or you will get a tuple which contains many strings!

Answered By: acgtyrant

Answer 6

When trying to enter continuous text (say, a query) do not put commas at the end of the line or you will get a list of strings instead of one long string:

queryText= "SELECT * FROM TABLE1 AS T1"
"JOIN TABLE2 AS T2 ON T1.SOMETHING = T2.SOMETHING"
"JOIN TABLE3 AS T3 ON T3.SOMETHING = T2.SOMETHING"
"WHERE SOMETHING BETWEEN <WHATEVER> AND <WHATEVER ELSE>"
"ORDER BY WHATEVERS DESC"

kinda like that.

There is a comment like this from acgtyrant, sorry, didn’t see that. :/

Answered By: kotbeg

Answer 7

DB related code looks easier on the eyes in multiple lines, enclosed by a pair of triple quotes:

SQL = """SELECT
            id, 
            fld_1, 
            fld_2, 
            fld_3, 
            ...... 
         FROM some_tbl"""

than the following one giant long line:

SQL = "SELECT id, fld_1, fld_2, fld_3, .................................... FROM some_tbl"

Answered By: Down the Stream

Is it possible to break a long line to multiple lines in Python?

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