Python string split using regex

Question

I need to parse a line like these:

foo, bar > 1.0, baz = 2.0
foo  bar > 1.0  baz = 2.0
foo, bar, baz
foo  bar  baz

for each element it can be $string (>|<|<=|>=|=) $num or just $string, separator ',' is optional between the elements.

in all these cases, recognize them as:

['foo', 'bar', 'baz']

how could I do this in python?

What happens if there is only foo, bar or bar > 1.0 baz = 2.0 in a line? — Anshul Goyal
– Anshul Goyal, Commented Nov 17, 2013 at 9:23

Anirudha · Accepted Answer · 2013-11-17 09:30:01Z

3

You can split at every non alphabetic characters

re.split("[^a-zA-Z]+",input)

Though am assuming that your $string contain only alphabets..

You can remove empty results with filter

filter(None, str_list)

edited Nov 17, 2013 at 9:30

answered Nov 17, 2013 at 9:21

Anirudha

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Comments

Inbar Rose · Accepted Answer · 2013-11-17 09:50:34Z

2

You can just extract all the letter groups:

s = """
foo, bar > 1.0, baz = 2.0
foo  bar > 1.0  baz = 2.0
foo, bar, baz
foo  bar  baz
"""

import re
regex = re.compile(r'([a-z]+)', re.I)  # re.I (ignore case flag)

for line in s.splitlines():
    if not line:
        continue # skip empty lines

    print regex.findall(line)

>>> 
['foo', 'bar', 'baz']
['foo', 'bar', 'baz']
['foo', 'bar', 'baz']
['foo', 'bar', 'baz']

edited Nov 17, 2013 at 9:50

answered Nov 17, 2013 at 9:25

Inbar Rose

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2 Comments

yuvi Over a year ago

should probably be [a-zA-Z]+ to include capitals as well, no?

Inbar Rose Over a year ago

Or use the ignorecase flag.

perreal · Accepted Answer · 2013-11-17 09:50:25Z

0

This one checks for the syntax also:

import re
with open("input") as f:
    for line in f:
        line = line.strip()
        # chop a line into expressions of the form: str [OP NUMBER]
        exprs = re.split(r'(\w+\s*(?:[!<>=]=?\s*[\d.]*)?\s*,?\s*)', line)
        for expr in exprs:
            # chop each expression into tokens and get the str part
            tokens = re.findall(r'(\w+)\s*(?:[!<>=]=?\s*[\d.]*)?,?', expr)
            if tokens: print tokens

answered Nov 17, 2013 at 9:50

perreal

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1 Comment

vts Over a year ago

This is very close to what I want, my question is not well described, it should be str [OP str], and str can contains number too, I'm trying to figure out a solution based on your answer, thanks very much.

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