Parsing a tweet to extract hashtags into an array

I am having a heck of a time taking the information in a tweet including hashtags, and pulling each hashtag into an array using Python. I am embarrassed to even put what I have been trying thus far.

For example, "I love #stackoverfl开发者_C百科ow because #people are very #helpful!"

This should pull the 3 hashtags into an array.

A simple regex should do the job:

>>> import re
>>> s = "I love #stackoverflow because #people are very #helpful!"
>>> re.findall(r"#(\w+)", s)
['stackoverflow', 'people', 'helpful']

Note though, that as suggested in other answers, this may also find non-hashtags, such as a hash location in a URL:

>>> re.findall(r"#(\w+)", "http://example.org/#comments")
['comments']

So another simple solution would be the following (removes duplicates as a bonus):

>>> def extract_hash_tags(s):
...    return set(part[1:] for part in s.split() if part.startswith('#'))
...
>>> extract_hash_tags("#test http://example.org/#comments #test")
set(['test'])

>>> s="I love #stackoverflow because #people are very #helpful!"
>>> [i  for i in s.split() if i.startswith("#") ]
['#stackoverflow', '#people', '#helpful!']

The best Twitter hashtag regular expression:

import re
text = "#promovolt #1st # promovolt #123"
re.findall(r'\B#\w*[a-zA-Z]+\w*', text)

>>> ['#promovolt', '#1st']

Suppose that you have to retrieve your #Hashtags from a sentence full of punctuation symbols. Let's say that #stackoverflow #people and #helpfulare terminated with different symbols, you want to retrieve them from text but you may want to avoid repetitions:

>>> text = "I love #stackoverflow, because #people... are very #helpful! Are they really #helpful??? Yes #people in #stackoverflow are really really #helpful!!!"

if you try with set([i for i in text.split() if i.startswith("#")]) alone, you will get:

>>> set(['#helpful???',
 '#people',
 '#stackoverflow,',
 '#stackoverflow',
 '#helpful!!!',
 '#helpful!',
 '#people...'])

which in my mind is redundant. Better solution using RE with module re:

>>> import re
>>> set([re.sub(r"(\W+)$", "", j) for j in set([i for i in text.split() if i.startswith("#")])])
>>> set(['#people', '#helpful', '#stackoverflow'])

Now it's ok for me.

EDIT: UNICODE #Hashtags

Add the re.UNICODE flag if you want to delete punctuations, but still preserving letters with accents, apostrophes and other unicode-encoded stuff which may be important if the #Hashtags may be expected not to be only in english... maybe this is only an italian guy nightmare, maybe not! ;-)

For example:

>>> text = u"I love #stackoverflòw, because #peoplè... are very #helpfùl! Are they really #helpfùl??? Yes #peoplè in #stackoverflòw are really really #helpfùl!!!"

will be unicode-encoded as:

>>> u'I love #stackoverfl\xf2w, because #peopl\xe8... are very #helpf\xf9l! Are they really #helpf\xf9l??? Yes #peopl\xe8 in #stackoverfl\xf2w are really really #helpf\xf9l!!!'

and you can retrieve your (correctly encoded) #Hashtags in this way:

>>> set([re.sub(r"(\W+)$", "", j, flags = re.UNICODE) for j in set([i for i in text.split() if i.startswith("#")])])
>>> set([u'#stackoverfl\xf2w', u'#peopl\xe8', u'#helpf\xf9l'])

EDITx2: UNICODE #Hashtags and control for # repetitions

If you want to control for multiple repetitions of the # symbol, as in (forgive me if the text example has become almost unreadable):

>>> text = u"I love ###stackoverflòw, because ##################peoplè... are very ####helpfùl! Are they really ##helpfùl??? Yes ###peoplè in ######stackoverflòw are really really ######helpfùl!!!"
>>> u'I love ###stackoverfl\xf2w, because ##################peopl\xe8... are very ####helpf\xf9l! Are they really ##helpf\xf9l??? Yes ###peopl\xe8 in ######stackoverfl\xf2w are really really ######helpf\xf9l!!!'

then you should substitute these multiple occurrences with a unique #. A possible solution is to introduce another nested implicit set() definition with the sub() function replacing occurrences of more-than-1 # with a single #:

>>> set([re.sub(r"#+", "#", k) for k in set([re.sub(r"(\W+)$", "", j, flags = re.UNICODE) for j in set([i for i in text.split() if i.startswith("#")])])])
>>> set([u'#stackoverfl\xf2w', u'#peopl\xe8', u'#helpf\xf9l']) 

AndiDogs answer will screw up with links and other stuff, you may want to filter them out first. After that use this code:

UTF_CHARS = ur'a-z0-9_\u00c0-\u00d6\u00d8-\u00f6\u00f8-\u00ff'
TAG_EXP = ur'(^|[^0-9A-Z&/]+)(#|\uff03)([0-9A-Z_]*[A-Z_]+[%s]*)' % UTF_CHARS
TAG_REGEX = re.compile(TAG_EXP, re.UNICODE | re.IGNORECASE)

It may seem overkill but this has been converted from here http://github.com/mzsanford/twitter-text-java. It will handle like 99% of all hashtags in the same way that twitter handles them.

For more converted twitter regex check out this: http://github.com/BonsaiDen/Atarashii/blob/master/atarashii/usr/share/pyshared/atarashii/formatter.py

EDIT:
Check out: http://github.com/BonsaiDen/AtarashiiFormat

simple gist (better than chosen answer) https://gist.github.com/mahmoud/237eb20108b5805aed5f also work with unicode hashtags

hashtags = [word for word in tweet.split() if word[0] == "#"]

i had a lot of issues with unicode languages.

i had seen many ways to extract hashtag, but found non of them answering on all cases

so i wrote some small python code to handle most of the cases. it works for me.

def get_hashtagslist(string):
    ret = []
    s=''
    hashtag = False
    for char in string:
        if char=='#':
            hashtag = True
            if s:
                ret.append(s)
                s=''           
            continue

        # take only the prefix of the hastag in case contain one of this chars (like on:  '#happy,but i..' it will takes only 'happy'  )
        if hashtag and char in [' ','.',',','(',')',':','{','}'] and s:
            ret.append(s)
            s=''
            hashtag=False 

        if hashtag:
            s+=char

    if s:
        ret.append(s)

    return list(set([word for word in ret if len(ret)>1 and len(ret)<20]))

I extracted hashtags in a silly but effective way.

def retrive(s):
    indice_t = []
    tags = []
    tmp_str = ''
    s = s.strip()
    for i in range(len(s)):
        if s[i] == "#":
            indice_t.append(i)
    for i in range(len(indice_t)):
        index = indice_t[i]
        if i == len(indice_t)-1:
            boundary = len(s)
        else:
            boundary = indice_t[i+1]
        index += 1
        while index < boundary:
            if s[index] in "`~!@#$%^&*()-_=+[]{}|\\:;'"",.<>?/ \n\t":
                tags.append(tmp_str)
                tmp_str = ''
                break
            else:
                tmp_str += s[index]
                index += 1
        if tmp_str != '':
            tags.append(tmp_str)
    return tags