Python ngrams to KWIC dictionary

ngrams-to-kwic-dict.py

# Given a list of n-grams, return a dictionary of KWICs,
# indexed by keyword.

def nGramsToKWICDict(ngrams):
    keyindex = len(ngrams[0]) // 2

    kwicdict = {}

    for k in ngrams:
      if k[keyindex] not in kwicdict:
        kwicdict[k[keyindex]] = [k]
      else:
        kwicdict[k[keyindex]].append(k)
    return kwicdict