Python in a Nutshell

Name

findall

Synopsis

                        r.findall(s)

When r has no groups, findall returns a list of strings, each a substring of s that is a non-overlapping match with r. For example, here’s how to print out all words in a file, one per line:

import re
reword = re.compile(r'\w+')
for aword in reword.findall(open('afile.txt').read( )):
    print aword

When r has one group, findall also returns a list of strings, but each is the substring of s matching r’s group. For example, if you want to print only words that are followed by whitespace (not punctuation), you need to change only one statement in the previous example:

reword = re.compile('(\w+)\s')

When r has n groups (where n is greater than 1), findall returns a list of tuples, one per non-overlapping match with r. Each tuple has n items, one per group of r, the substring of s matching the group. For example, here’s how to print the first and last word of each line that has at least two words:

import re
first_last = re.compile(r'^\W*(\w+)\b.*\b(\w+)\W*$', 
                                      re.MULTILINE)
for first, last in \
first_last.findall(open('afile.txt').read( )):
    print first, last