I have some sentences.
text = [ "Call me Ishmael.", "Some years ago, never mind how long precisely, having little or no money..." ]
How many words are in each sentence?
for sentence in text: sentenceLength = len(sentence.split()) print(sentenceLength) 3 13
But I want to do it all at once the functional programming way, with maps.
list(map(len, map(split, text))) NameError: name 'split' is not defined
Why does that produce an error? Because “split” isn’t a function. It’s a method of strings: str.split(), not split(str).
So how do we use map with a class method?
from operator import methodcaller
split = methodcaller("split")
That means, “Create a function. I’ll pass in an object. Call its ‘split’ method.”
Now it works.
list(map(len, map(split, text))) [3, 13]
Of course, there are other ways. Don’t even need map.
[len(s.split()) for s in text]