Python

Cutting a string in equal pieces

Gribouillis Gribouillis is offline

Offline Jul 30th, 2008, 7:04 pm |

This snippet shows a fast and efficient way to cut strings in substrings with a fixed length (note that the last substring may be smaller).

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import re
split5 = re.compile(r".{1,5}", re.DOTALL).findall
 
if __name__ == "__main__":
    print split5('"Give me bacon and eggs," said the other man.')
    # prints ['"Give', ' me b', 'acon ', 'and e', 'ggs,"', ' said', ' the ', 'other', ' man.']

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Gribouillis Gribouillis is offline

Offline | Jul 31st, 2008

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An alternative is this

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splitIt =  lambda d, s: [s[i:i+d] for i in range(0, len(s), d)]
 
if __name__ == "__main__":
    print splitIt(5, '"Give me bacon and eggs," said the other man.')
splitIt =  lambda d, s: [s[i:i+d] for i in range(0, len(s), d)]

if __name__ == "__main__":
    print splitIt(5, '"Give me bacon and eggs," said the other man.')

Gribouillis Gribouillis is offline

Offline | Oct 20th, 2009

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The following benchmark shows that, on my machine, split5() is about 22% faster than splitIt()

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# benchmark for split5 and splitIt (tested with python 2.6)
from timeit import Timer
import re
split5 = re.compile(r".{1,5}", re.DOTALL).findall
splitIt =  lambda d, s: [s[i:i+d] for i in range(0, len(s), d)]
 
if __name__=='__main__':
 
    t = Timer("split5('Give me bacon and eggs, said the other man.')", "from __main__ import split5")
    print "split5: %.2f microsec"  % t.timeit()
    t = Timer("splitIt(5, 'Give me bacon and eggs, said the other man.')", "from __main__ import splitIt")
    print "splitIt: %.2f microsec"  % t.timeit()
 
""" my output --->
split5: 2.55 microsec
splitIt: 3.27 microsec
"""
# benchmark for split5 and splitIt (tested with python 2.6)
from timeit import Timer
import re
split5 = re.compile(r".{1,5}", re.DOTALL).findall
splitIt =  lambda d, s: [s[i:i+d] for i in range(0, len(s), d)]

if __name__=='__main__':

    t = Timer("split5('Give me bacon and eggs, said the other man.')", "from __main__ import split5")
    print "split5: %.2f microsec"  % t.timeit()
    t = Timer("splitIt(5, 'Give me bacon and eggs, said the other man.')", "from __main__ import splitIt")
    print "splitIt: %.2f microsec"  % t.timeit()

""" my output --->
split5: 2.55 microsec
splitIt: 3.27 microsec
"""

however, you can gain 0.2 microsecs by replacing range with xrange in splitIt()