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How to fix Python indentation

I have some Python code that have inconsistent indentation. There is a lot of mixture of tabs and spaces to make the matter even worse, and even space indentation is not preserved.

The code works as expected, but it's difficult to maintain.

How can I fix the indentation (like HTML Tidy, but for Python) without breaking the code?

autopep8

12 Answers
12

Use the reindent.py script that you find in the Tools/scripts/ directory of your Python installation:

reindent.py

Tools/scripts/

Change Python (.py) files to use
4-space indents and no hard tab
characters. Also trim excess spaces
and tabs from ends of lines, and
remove empty lines at the end of
files. Also ensure the last line ends
with a newline.

Have a look at that script for detailed usage instructions.

python-examples

python-examples

/usr/share/doc/pythonX.X/examples/Tools/scripts/reindent.py

If you're using Vim, see :h retab.

:h retab

For example, if you simply type

all your tabs will be expanded into spaces.

You may want to

to make sure that any new lines will not use literal tabs.

If you're not using Vim,

will replace tabs with spaces, assuming tab stops every 8 characters, in file.py (with the original going to file.py.bak, just in case). Replace the 8s with 4s if your tab stops are every 4 spaces instead.

file.py

file.py.bak

I would reach for autopep8 to do this:

$ # see what changes it would make
$ autopep8 path/to/file.py --select=E101,E121 --diff

$ # make these changes
$ autopep8 path/to/file.py --select=E101,E121 --in-place


Note: E101 and E121 are pep8 indentation (I think you can simply pass --select=E1 to fix all indentation related issues - those starting with E1).

--select=E1

You can apply this to your entire project using recursive flag:

$ autopep8 package_dir --recursive --select=E101,E121 --in-place


See also Tool to convert Python code to be PEP8 compliant.

autopep8

python -tt <file.py>

Use autopep8

autopep8 automagically formats Python code to conform to the PEP 8
nullstyle guide. It uses the pep8 utility to determine what parts of the
nullcode needs to be formatted. autopep8 is capable of fixing most of the
nullformatting issues that can be reported by pep8.

autopep8

PEP 8

nullstyle

nullcode

autopep8

nullformatting

pep8

pip install autopep8
autopep8 script.py # print only
autopep8 -i script.py # write file


Using Vim, it shouldn't be more involved than hitting Esc, and then typing...

:%s/t/ /g


...on the file you want to change. That will convert all tabs to four spaces. If you have inconsistent spacing as well, then that will be more difficult.

There is also PythonTidy (since you said you like HTML Tidy).

It can do a lot more than just clean up tabs though. If you like that type of thing, it's worth a look.

If you're lazy (like me), you can also download a trial version of Wingware Python IDE, which has an auto-fix tool for messed up indentation. It works pretty well.
http://www.wingware.com/

On most UNIX-like systems, you can also run:

expand -t4 oldfilename.py > newfilename.py


from the command line, changing the number if you want to replace tabs with a number of spaces other than 4. You can easily write a shell script to do this with a bunch of files at once, retaining the original file names.

The reindent script did not work for me, due to some missing module. Anyway, I found this sed command which does the job perfect for me:

sed

sed -r 's/^([ ]*)([^ ])/112/' file.py


Try Emacs. It has good support for indentation needed in Python. Please check this link http://python.about.com/b/2007/09/24/emacs-tips-for-python-programmers.htm

I have a simple solution for this problem. You can first type ":retab" and then ":retab!", then everything would be fine

:retab

Try IDLE, and use Alt + X to find indentation.

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