在Python中重复正则表达式模式

Question

I have a file with millions of retweets – like this:

RT @Username: Text_of_the_tweet

I just need to extract the username from this string. Since I'm a total zero when it comes to regex, sometime ago here I was advised to use

username = re.findall('@([^:]+)', retweet)

This works great for the most part, but sometimes I get lines like this:

RT @ReutersAero: Further pictures from the #MH17 crash site in  in Grabovo, #Ukraine #MH17 - @reuterspictures (GRAPHIC): http://t.co/4rc7Y4…

I only need "ReutersAero" from the string, but since it contains another "@" and ":" it messes up the regex, and I get this output:

['ReutersAero', 'reuterspictures (GRAPHIC)']

Is there a way to use the regex only for the first instance it finds in the string?

Answer 1

You can use a regex like this:

RT @(\w+):

Working demo

Match information:

MATCH 1
1.  [4-15]  `ReutersAero`
MATCH 2
1.  [145-156]   `AnotherAero`

You can use this python code:

import re
p = re.compile(ur'RT @(\w+):')
test_str = u"RT @ReutersAero: Further pictures from the #MH17 crash site in  in Grabovo, #Ukraine #MH17 - @reuterspictures (GRAPHIC): http://t.co/4rc7Y4…\nRT @AnotherAero: Further pictures from the #MH17 crash site in  in Grabovo, #Ukraine #MH17 - @reuterspictures (GRAPHIC): http://t.co/4rc7Y4…\n"

re.findall(p, test_str)

Answer 2

Is there a way to use the regex only for the first instance it finds in the string?

Do not use findall , but search .