parse commands with regex and python

Question

I have a string like this:

str = "something move 11 something move 12 something 13 copy 14 15"

where the "something" means some text, or no text at all.
and as a result I want to have a list like:

[('move', 11, ''), ('move', 12, 13), ('copy', 14, 15)]

I tried using this:

re.findall('(move|copy).+?([0-9]+).+?([0-9]+)*', str)

but it gives my the output:

[('move', 11, ''), ('move', 12, ''), ('copy', 14, '')]

I understand that is because the last number is optional, but I just have no idea how I could it get working.

How can I do this?

You cannot do it if you expect any number of arguments to the commands. You can only tokenize the string and pick out the commands from an array of tokens. — nhahtdh
– nhahtdh, Commented Jan 23, 2013 at 20:48

Community · Accepted Answer · 2017-05-23 12:12:17Z

1

Based on @Ashwini Chaudhary's answer:

#!/usr/bin/env python
import re

commands = "copy move".split()
input_string  = "something move 11 something move 12 something 13 copy 14 15"
tokens = iter(re.split("(%s)" % "|".join(map(re.escape, commands)), input_string))
result = []
for tok in tokens:
     if tok in commands:
        args = re.findall(r"\d+", next(tokens, ""))
        result.append((tok,) + tuple(args) + ("",)*(2 - len(args)))
print(result)

Output

[('move', '11', ''), ('move', '12', '13'), ('copy', '14', '15')]

To limit each command to two arguments, just use slicing: tuple(arg[:2]).

edited May 23, 2017 at 12:12

CommunityBot

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answered Jan 23, 2013 at 21:41

jfs

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Comments

Andy Hayden · Accepted Answer · 2013-01-23 21:34:57Z

1

You could use a regular expression (with lookbehind and lookahead):

In [1]: import re

In [2]: tokens = "something move 11 something move 12 something 13 copy 14 15"

In [3]: split_movements = re.split('(?<=\d)\s(?!\d+)', tokens)

In [4]: split_movements
Out[4]: ['something move 11', 'something move 12', 'something 13', 'copy 14 15']

In [5]: movements = [re.split('\s(?=\d+)', m) for m in split_movements]

In [6]: movements
Out[6]: 
[['something move', '11'],
 ['something move', '12'],
 ['something', '13'],
 ['copy', '14', '15']]

answered Jan 23, 2013 at 21:34

Andy Hayden

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