how do i extract a partial value from a string in python?

Question

I have the following string:

(1, 2, 3, 4)

I want to convert it to just the last two values:

(3, 4)

In my actual code all four fields are whole numbers but vary greatly in length. I've tried doing this with both regex and 'for' statements as well as trying the various answers to similar questions here on SO but so far no luck.

String is = "This is String" | List = [1,2,3,4,5] | Tuple = (1,2,3,4) — Sudantha
– Sudantha, Commented Jul 17, 2011 at 14:25

joaquin · Accepted Answer · 2011-07-17 14:21:23Z

5

This gives you the last two terms in your tuple:

>> a = (1,2,3,4)
>> a[-2:]
(3,4)

answered Jul 17, 2011 at 14:21

joaquin

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1 Comment

hef Over a year ago

at first that didn't work but only because I was converting my tuple to a string (oops). Thanks :)

Artsiom Rudzenka · Accepted Answer · 2011-07-21 10:32:39Z

0

If (1,2,3,4) is tuple:

data = (1,2,3,4)
newData = data[-2:]

If you have '(1,2,3,4)' then:

import ast
data = ast.literal_eval('(1,2,3,5)')
newData = data[-2:]

Or in case you have to split such list in a certain value:

def get_slice(inputData, searchVal):   
    if searchVal in inputData and inputData.index(searchVal) < len(inputData):
        return inputData[inputData.index(searchVal)+1:]
    return ()

get_slice((1,2,3,4),2)

edited Jul 21, 2011 at 10:32

answered Jul 17, 2011 at 14:27

Artsiom Rudzenka

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4 Comments

Tim Pietzcker Over a year ago

ObWarning: eval() is evil. (In case he doesn't control where the string is coming from).

SingleNegationElimination Over a year ago

Nuuuuuu! use ast.literal_eval()

Artsiom Rudzenka Over a year ago

I fully agree with you - it was just a sample in case he has a string mentioned in the question. Sure i know that string could be splited and so on.

SingleNegationElimination Over a year ago

@tim: even when you do control where it's coming from, it's evil. You control it; use pickle or json or anything else.

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