[FIXED] How to write to the file with a variable .format?

Issue

I want to write two strings into a file with variable white-spaces between. Here's the code I wrote:

width = 6
with open(out_file, 'a') as file:
    file.write("{:width}{:width}\n".format('a', 'b'))

But I get ValueError: Invalid conversion specification from it. I expected it to write characters a and b with 6 spaces between in one line into the file.

I am using python 2.

Solution

You need to change the format string a little and pass width as a keyword argument to the format() method:

width = 6
with open(out_file, 'a') as file:
    file.write("{:{width}}{:{width}}\n".format('a', 'b', width=width))

Contents of file afterwards:

a     b     

Answered By - martineau