autocomplete.py - redis autocompleter

autocomplete.py

"""
A redis autocomplete example for multi-word phrases.

Based on:
  Ruby original: http://gist.github.com/574044
  Python original: https://gist.github.com/577852

See options below for usage

Requires http://github.com/andymccurdy/redis-py/
"""

from redis import Redis
import sys

r = Redis()
ZKEY_COMPL = 'compl'
SKEY_DOCS_PREFIX = 'docs:'

def deleteAll():
    """Clear out the completions db"""
    return r.zremrangebyrank(ZKEY_COMPL, 0, -1)

def addCompletions(text):
    """Create the completion sorted set."""
    text = text.strip()
    if not text:
        return

    for word in text.split():
        word = word.lower()
        for end_index in range(1, len(word)+1):
            prefix = word[:end_index]
            r.zadd(ZKEY_COMPL, prefix, 0)
        r.zadd(ZKEY_COMPL, word + '*', 0)     
        r.sadd(SKEY_DOCS_PREFIX + word, text)

    r.zadd(ZKEY_COMPL, text + '*', 0)
    r.sadd(SKEY_DOCS_PREFIX + text.lower(), text)

def addFromFile(filename):
    """Create completions for all lines in filename"""
    print "Adding completions for", filename, "...",
    sys.stdout.flush()
    for line in open(filename):
        addCompletions(line)
    print "done"

def getWordCompletions(r, word, count, rangelen=50):
    """Get up to count completions for the given word"""
    prefix = word.lower().strip()
    results = set()
    if not prefix:
        return results

    start = r.zrank(ZKEY_COMPL, prefix)
    if start is None:
        return results

    while len(results) <= count:
        entries = r.zrange(ZKEY_COMPL, start, start + rangelen - 1)
        start += rangelen

        if not entries or len(entries) == 0:
            break

        for entry in entries:
            minlen = min((len(entry), len(prefix)))
            if entry[:minlen] != prefix[:minlen]:
                return results

            if entry[-1] == '*' and len(results) <= count:
                results.add(entry[0:-1])

    return results

def getPhraseCompletions(r, text, count):
    """
    Get up to @count completions for @text

    For an input text of N words, uses N+1 redis calls: 
    One ZRANK per word, and one SUNION at the end.
    """
    results = set()
    for prefix in text.lower().split():
        results.update(getWordCompletions(r, prefix, count))

    keys = map(lambda k: SKEY_DOCS_PREFIX+k, results) 
    if keys:
        return sorted(r.sunion( keys ), key=str.lower)[:count]
    else:
        return []

if __name__ == '__main__':
    from optparse import OptionParser
    parser = OptionParser()

    parser.add_option("-f", "--file", dest="filename",
                      help="Create completions for lines in FILE", metavar="FILE")
    parser.add_option("-i", "--insert", dest="text",
                      help="Create completions for TEXT", metavar="TEXT")
    parser.add_option("-d", "--delete-all", dest="delete", 
                      action="store_true", default=False,
                      help="Delete everything in the completions db")

    (options, args) = parser.parse_args()
    
    if options.delete:
        deleteAll()

    if options.filename:
        addFromFile(options.filename)

    if options.text:
        addCompletions(options.text)

    if args:
        for arg in args:
            print arg, '==>'
            print '\n'.join(getPhraseCompletions(r, arg, 10))
        

Note that in getWordCompletions on line 57, you'll return early for the first element of the ZSET. That is because ZSETs are indexed from 0. So your test doesn't pass. Change line 57 to read:

if start is None:

and you should be good to go.

Right you are, streeter. Thank you for that catch. Cheers,
j