word frequency program in python

python dictionary word-frequency
user637965 picture user637965 · Mar 8, 2011 · Viewed 10.1k times · Source

Say I have a list of words called words i.e. words = ["hello", "test", "string", "people", "hello", "hello"] and I want to create a dictionary in order to get word frequency.

Let's say the dictionary is called 'counts'

counts = {}
for w in words:
    counts[w] = counts.get(w,0) + 1

The only part of this I don't really understand is the counts.get(w.0). The book says, normally you would use counts[w] = counts[w] + 1 but the first time you encounter a new word, it won't be in counts and so it would return a runtime error. That all fine and dandy but what exactly does counts.get(w,0) do? Specifically, what's the (w,0) notation all about?

Answer

samplebias picture samplebias · Mar 8, 2011

If you have a dictionary, get() is a method where w is a variable holding the word you're looking up and 0 is the default value. If w is not present in the dictionary, get returns 0.

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