I'm reading http://norvig.com/spell-correct.html
and do not understand the expression listed in the subject which is
part of this function:
def train(features):
model = collections.defaultdict(lambda: 1)
for f in features:
model[f] += 1
return model
Per http://docs.python.org/lib/defaultdict-examples.html
It seems that there is a default factory which initializes each key to
1. So by the end of train(), each member of the dictionary model will
have value >= 1
But why wouldnt he set the value to zero and then increment it each
time a "feature" (actually a word) is encountered? It seems that each
model value would be 1 more than it should be.
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