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Assume I have a list of words, and I want to find the number of times each word appears in that list.
An obvious way to do this is:
words = "apple banana apple strawberry banana lemon" uniques = set(words.split()) freqs = [(item, words.split().count(item)) for item in uniques] print(freqs) But I find this code not very good, because the program runs through the word list twice, once to build the set, and a second time to count the number of appearances.
Of course, I could write a function to run through the list and do the counting, but that wouldn't be so Pythonic. So, is there a more efficient and Pythonic way?
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The most straightforward way to get the number of elements in a list is to use the Python built-in function len() . As the name function suggests, len() returns the length of the list, regardless of the types of elements in it.
We can use the counter() method from the collections module to count the frequency of elements in a list. The counter() method takes an iterable object as an input argument. It returns a Counter object which stores the frequency of all the elements in the form of key-value pairs.
The tally or frequency count is the calculation of how many people fit into a certain category or the number of times a characteristic occurs. This calculation is expressed by both the absolute (actual number) and relative (percentage) totals.
The Counter class in the collections module is purpose built to solve this type of problem:
from collections import Counter words = "apple banana apple strawberry banana lemon" Counter(words.split()) # Counter({'apple': 2, 'banana': 2, 'strawberry': 1, 'lemon': 1}) If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
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