Appending string to a list of strings

Question

import re
red_dict= {u'Jharkhand': ['jarka09', 'jarka05'],
 u'Karnataka': ['karnataka2013', 'karnatka2008']}
for key, value in red_dict.items():
    num = re.findall(r'\d+',' '.join(value))
    map(lambda x: x if len(x)==4 else '20'+x, num)
    print num

Getting the result

['09', '05']
['2013', '2008']

Why wasn't '20' appended to the two digit list items?

For ordinary use, I can verify that this approach works

l = ['a','b','cd']
map(lambda x:x if len(x)==2 else 'e'+x,l)

gives

['ea', 'eb', 'cd']

Abhijit · Accepted Answer · 2014-01-28 05:46:16Z

4

@falsetru's answer might solve your issue, but just a well formed regex could actually do your Job without any post processing with map

Implementation

for key, value in red_dict.items():
    print [re.sub("^[^\d]+20|[^\d]+", "20", v) for v in value]

Demo

['2009', '2005']
['2013', '2008']

Note

For your particular case, you would actually not even need a Regex. You can simply slice out the trailing two characters and append it to '20'

for key, value in red_dict.items():
    print ['20' + v[-2:] for v in value]

edited Jan 28, 2014 at 5:46

answered Jan 28, 2014 at 5:40

Abhijit

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1 Comment

falsetru Over a year ago

Use \D instead of [^\d]. + Use r'raw string' for regular expression (especially if there's any backslash).

falsetru · Accepted Answer · 2014-01-28 05:35:47Z

2

map does not replace the given num. You should assign the return value back to num.

>>> a = [1, 2, 3]
>>> map(lambda x: x + 1, a)
[2, 3, 4]
>>> a
[1, 2, 3]
>>> a = map(lambda x: x + 1, a)
>>> a
[2, 3, 4]

num = map(lambda x: x if len(x)==4 else '20'+x, num)
#^^^^

answered Jan 28, 2014 at 5:35

falsetru

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