Pre-PEP: Dictionary accumulator methods

Jeff Epler jepler at
Sat Mar 19 15:00:48 CET 2005

> [Jeff Epler]
> > Maybe something for sets like 'appendlist' ('unionset'?)
On Sat, Mar 19, 2005 at 04:18:43AM +0000, Raymond Hettinger wrote:
> I do not follow.  Can you provide a pure python equivalent?

Here's what I had in mind:

$ python /tmp/
Set(['set', 'self', 'since', 's', 'sys', 'source', 'S', 'Set', 'sets', 'starting'])

    from sets import Set as set

def unionset(self, key, *values):
    except KeyError:
        self[key] = set(values)

if __name__ == '__main__':
    import sys, re
    index = {}

    # We need a source of words.  This file will do.
    corpus = open(sys.argv[0]).read()
    words = re.findall('\w+', corpus)

    # Create an index of the words according to the first letter.
    # repeated words are listed once since the values are sets
    for word in words:
        unionset(index, word[0].lower(), word)

    # Display the words starting with 'S'
    print index['s']

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