how to parse this string in Python? [duplicate]

Question

I have a file which contains each line in the following format

"('-1259656819525938837', 598679497)\t0.036787946"    # "\t" within the string is the tab sign

I need to get the components out

-1259656819525938837  #string, it is the content within ' '
598679497     # long
0.036787946   # float

Python 2.6

There are many tools for parsing strings. In order of increasing power and complexity they are 1: functions such as split, 2: regular expressions, 3: full fledged parsers. This task seems simple enough for split. — Johan Råde
– Johan Råde, Commented May 22, 2014 at 6:47
sorry to ask dumb questions, I was not aware of findall function. It should be closed now. — Jin
– Jin, Commented May 22, 2014 at 7:05

Marcin · Accepted Answer · 2014-05-22 06:56:47Z

1

You can use regular expressions from re module:

import re
s = "('-1259656819525938837', 598679497)\t0.036787946"
re.findall(r'[-+]?[0-9]*\.?[0-9]+', s)
% gives: ['-1259656819525938837', '598679497', '0.036787946']

answered May 22, 2014 at 6:56

Marcin

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Pavan Gupta · Accepted Answer · 2014-05-22 06:49:00Z

0

"2.7.0_bf4fda703454".split("_") gives a list of strings:

In [1]: "2.7.0_bf4fda703454".split("_")
Out[1]: ['2.7.0', 'bf4fda703454']

This splits the string at every underscore. If you want it to stop after the first split, use "2.7.0_bf4fda703454".split("_", 1).

If you know for a fact that the string contains an underscore, you can even unpack the LHS and RHS into separate variables:

In [8]: lhs, rhs = "2.7.0_bf4fda703454".split("_", 1)

In [9]: lhs
Out[9]: '2.7.0'

In [10]: rhs
Out[10]: 'bf4fda703454'

answered May 22, 2014 at 6:49

Pavan Gupta

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cuonglm · Accepted Answer · 2014-05-22 06:55:03Z

0

You can use a regex to extract number and float from string:

>>> import re
>>> a = "('-1259656819525938837', 598679497)\t0.036787946"
>>> re.findall(r'[-?\d\.\d]+', a)
['-1259656819525938837', '598679497', '0.036787946']

answered May 22, 2014 at 6:55

cuonglm

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1 Comment

Jarno Lamberg Over a year ago

Actually, the character set in your regular expression is misleading. You probably meant it in a different way. Otherwise, if you still want to use a character set, maybe a simpler one would suffice: re.findall(r'[-\d\.]+', a)

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