Regexy thing for matching tags out of strings. You define a thing, ARTS, which is just a list of what you want to match, then follow syntax below to return either a dict of counts or a list of things with nonzero counts. I'm actually pretty pleased with the performance of this that it keeps working fairly quickly even as the string size approach…

tagger.py

import re

ARTS = ['dance','photography','art therapy']

def string_found(string1, string2):
   if re.search(r"\b" + re.escape(string1) + r"\b", string2):
      return 1
   return 0

def string_count(string1, string2):
    pos = 0
    count = 0
    while pos <  len(string2):
        v = re.search(r"\b" + re.escape(string1) + r"\b", string2[pos:])
        if v:
            count += 1
            pos += v.end()
        else:
            break
    return(count)

makecounts = lambda mystr, tags: {k: string_count(k,mystr.lower()) for k in tags}
gettags = lambda mydict : filter(None,[m for m,vv in mydict.items() if vv>0])
tagger = lambda mystr, tags : gettags(makecounts(mystr,tags))

x = "A wonderful string about art therapy, photography, and architecture!"
makecounts(x,ARTS)
{'dance': 0, 'photography': 1, 'art therapy': 1}

tagger(x, ARTS)
['photography', 'art therapy']