Dictionariesdicts-word-counts
Lesson·difficulty 2/5·~12 min
Dicts: counting words
Dictionaries
A dictionary maps keys to values:
python
ages = {"Ada": 27, "Linus": 54}
ages["Ada"] # 27
ages["Grace"] = 105 # add a new key
"Linus" in ages # True
You can iterate over a dict in three useful ways:
python
for key in ages: # keys
...
for value in ages.values(): # values
...
for key, value in ages.items(): # both
...
Your task
Write a function word_counts(words) that takes a list of strings and
returns a dictionary mapping each word to the number of times it appears
(case-sensitive — "Hi" and "hi" are different keys).
python
word_counts(["a", "b", "a", "a", "b", "c"])
# {"a": 3, "b": 2, "c": 1}
word_counts([])
# {}
Tests
- basic
- empty
- single
- case sens (hidden)
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