Python regex, fetch names from a string

Question

I have a string in the form of:

"[NUM : NAME : NUM]: [NUM : NAME : NUM]:..."

I want to be able to extract all the NAMEs out of this string. The NAME can have any character, ranging from alphabet to punctuation symbols and numbers. NUM is only in the form of [0-9]+

I tried issuing this command:

re.findall(r"\[[0-9]+\:([.]+)\:[0-9]+\]", string)

But instead of giving what I requested, it would bunch up a few [NUM : NAME : NUM]s into the [.]+ group, which is also correct in terms of this regex, but not what I need.

Any help would be much appreciated.

Brian · Accepted Answer · 2013-01-18 17:04:43Z

2

Try this:

re.findall(r"\[[0-9]+\:(.+?)\:[0-9]+\]", string)

Adding the ? after the + is non-greedy. Greedy means that the + will take as many characters as possible while still matching and it is greedy by default. By adding the ? you are telling it to be non-greedy, which means the + will take the minimum number of characters to match.

The above will work if there are no spaces between num, :, and name.

If there are spaces then use:

re.findall(r"\[[0-9]+ \: (.+?) \: [0-9]+\]", string)

answered Jan 18, 2013 at 17:04

Brian

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Comments

Rohit Jain · Accepted Answer · 2013-01-18 17:10:23Z

1

First problem is that you have enclosed . inside a character class. So, you have lost the meaning of ., and it only matches just a dot(.).
Secondly, you are not considering spaces after the numbers in your string.
Thirdly, you need to use reluctant quantifier with your .+ in the center. So, replace - ([.]+) with (.+?).
Fourthly, you don't need to escape your colons (:).

You can try out this: -

>>> re.findall(r'\[[0-9]+[ ]*:(.+?):[ ]*[0-9]+\]', string)
6: [' NAME ', ' NAME ']

edited Jan 18, 2013 at 17:10

answered Jan 18, 2013 at 17:03

Rohit Jain

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1 Comment

Yarneo Over a year ago

Thank you Rohit, your version works well, and your explanation helped me to better understand regex.

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