Fastest way to calculate leading whitespace

[Daniel Skinner]

sorry, my mistake it runs faster (looking at the wrong line of code). But
the first two solutions are still faster.

On Sat, May 8, 2010 at 12:48 PM, Daniel Skinner <dasacc22 at gmail.com> wrote:

> That solution actually runs slower then the generator method.
>
>
> On Sat, May 8, 2010 at 12:33 PM, Shashank Singh <
> shashank.sunny.singh at gmail.com> wrote:
>
>>
>>
>> On Sat, May 8, 2010 at 10:49 PM, dasacc22 <dasacc22 at gmail.com> wrote:
>>
>>> Hi
>>>
>>> This is a simple question. I'm looking for the fastest way to
>>> calculate the leading whitespace (as a string, ie '    ').
>>>
>>> Here are some different methods I have tried so far
>>> --- solution 1
>>>
>>> a = '    some content\n'
>>> b = a.strip()
>>> c = ' '*(len(a)-len(b))
>>>
>>
>> use lstrip if you want to remove leading whitespaces only.
>> strip removes trailing white spaces too
>>
>>>
>>> --- solution 2
>>>
>>> a = '    some content\n'
>>> b = a.strip()
>>> c = a.partition(b[0])[0]
>>>
>>> --- solution 3
>>>
>>> def get_leading_whitespace(s):
>>>    def _get():
>>>        for x in s:
>>>            if x != ' ':
>>>                break
>>>            yield x
>>>    return ''.join(_get())
>>>
>>
>> why do you need a generator (and as you mentioned the extra function call
>> overheads)?
>>
>> How about this?
>>
>> def get_leading_whitespaces(s):
>>     count = 0
>>     for c in s:
>>         if c != ' ': break
>>         count += 1
>>     return ' ' * count
>>
>>
>>>
>>> ---
>>>
>>> Solution 1 seems to be about as fast as solution 2 except in certain
>>> circumstances where the value of b has already been determined for
>>> other purposes. Solution 3 is slower due to the function overhead.
>>>
>>> Curious to see what other types of solutions people might have.
>>>
>>> Thanks,
>>> Daniel
>>> --
>>> http://mail.python.org/mailman/listinfo/python-list
>>>
>>
>>
>>
>> --
>> Regards
>> Shashank Singh
>> Senior Undergraduate, Department of Computer Science and Engineering
>> Indian Institute of Technology Bombay
>> shashank.sunny.singh at gmail.com
>> http://www.cse.iitb.ac.in/~shashanksingh
>>
>
>
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