Extracting a string between specified characters in python

Question

I'm a newbie to regular expressions and I have the following string:

sequence = '["{\"First\":\"Belyuen,NT,0801\",\"Second\":\"Belyuen,NT,0801\"}","{\"First\":\"Larrakeyah,NT,0801\",\"Second\":\"Larrakeyah,NT,0801\"}"]'

I am trying to extract the text Belyuen,NT,0801 and Larrakeyah,NT,0801 in python. I have the following code which is not working:

re.search('\:\\"...\\', ''.join(sequence))

I.e. I want to get the string between characters :\ and \.

Daniel Roseman · Accepted Answer · 2010-04-03 13:46:11Z

3

Don't use regex for this. It appears to be a rather strangely split set of JSON strings. Join them back together and use the json module to decode it.

import json
sequence = '[%s]' % ','.join(sequence)
data = json.loads(sequence)
print data[0]['First'], data[0]['Second']

(Note the json module is new in Python2.6 - if you have a lower version, download and install simplejson).

answered Apr 3, 2010 at 13:46

Daniel Roseman

602k68 gold badges911 silver badges924 bronze badges

Sign up to request clarification or add additional context in comments.

4 Comments

Seth Over a year ago

the sequence is actually of string type (I updated question). the interpreter keeps throwing an error for the line data = json.loads(sequence) and the error is raise ValueError(errmsg("Expecting object", s, end))

Seth Over a year ago

if I scrap the second line of your code and print data[0] I get: {"First":"Belyuen,NT,0801","Second":"Belyuen,NT,0801"}

Seth Over a year ago

and if I print data[0]['First'] it comes up with the following error: ` print data[0]['First'] TypeError: string indices must be integers`

Seth Over a year ago

I ended up being able to extract what I wanted by doing the following: ` data = json.loads(sequence) /n location = json.loads(data[0]) /n print location['First']`

SilentGhost · Accepted Answer · 2010-04-03 13:46:43Z

3

it seems like a proper serialization of the Python dict, you could just do:

>>> sequence = ["{\"First\":\"Belyuen,NT,0801\",\"Second\":\"Belyuen,NT,0801\"}","{\"First\":\"Larrakeyah,NT,0801\",\"Second\":\"Larrakeyah,NT,0801\"}"]
>>> import json
>>> for i in sequence:
    d = json.loads(i)
    print(d['First'])


Belyuen,NT,0801
Larrakeyah,NT,0801

answered Apr 3, 2010 at 13:46

SilentGhost

322k67 gold badges312 silver badges294 bronze badges

3 Comments

Seth Over a year ago

the sequence is actually a string not list ( I updated the question ). so how do I load it into the json module as a string?

SilentGhost Over a year ago

@seth: unfortunately, it seems that the quotes in your input string are misused. it doesn't work either with json or eval. If you fix them, using alternate single and double quote, escaped where needed, then it works just fine with the method I showed. Again, quotes within string should be alternating, quotes that were used for original Python string, should be, of course, escaped.

Seth Over a year ago

thanks for your response, check out my comments in Daniel Roseman's answer. I ended up extracting what I needed in a convoluted way, but got it nevertheless. +1 for your help and useful answer.

ghostdog74 · Accepted Answer · 2010-04-03 13:47:47Z

2

you don't need regex

>>> sequence = ["{\"First\":\"Belyuen,NT,0801\",\"Second\":\"Belyuen,NT,0801\"}","{\"First\":\"Larrakeyah,NT,0801\",\"Second\":\"Larrakeyah,NT,0801\"}"]
>>> for item in sequence:
...  print eval(item).values()
...
['Belyuen,NT,0801', 'Belyuen,NT,0801']
['Larrakeyah,NT,0801', 'Larrakeyah,NT,0801']

answered Apr 3, 2010 at 13:47

ghostdog74

346k62 gold badges264 silver badges349 bronze badges

1 Comment

ghostdog74 Over a year ago

solution works in version <2.6. And i don't want to download any other modules.

Collectives™ on Stack Overflow

Extracting a string between specified characters in python

3 Answers 3

4 Comments

3 Comments

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

4 Comments

3 Comments

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related