What is the pythonic way to count the leading spaces in a string?

Question

I know I can count the leading spaces in a string with this:

>>> a = \"   foo bar baz qua   \\n\"
>>> print \"Leading spaces\", len(a) - le         


        

Answer 1

Just for variety, you could theoretically use regex. It's a little shorter, and looks nicer than the double call to len().

>>> import re
>>> a = "   foo bar baz qua   \n"
>>> re.search('\S', a).start() # index of the first non-whitespace char
3

Or alternatively:

>>> re.search('[^ ]', a).start() # index of the first non-space char
3

But I don't recommend this; according to a quick test I did, it's much less efficient than len(a)-len(lstrip(a)).