_.countBy(collection, [iteratee=_.identity])
Creates an object composed of keys generated from the results of running each element of collection
thru iteratee
. The corresponding value of each key is the number of times the key was returned by iteratee
. The iteratee is invoked with one argument: (value).
Since
0.5.0
Arguments
-
collection
(Array|Object): The collection to iterate over. -
[iteratee=_.identity]
(Function): The iteratee to transform keys.
Returns
(Object): Returns the composed aggregate object.
Example
_.countBy([6.1, 4.2, 6.3], Math.floor); // => { '4': 1, '6': 2 } // The `_.property` iteratee shorthand. _.countBy(['one', 'two', 'three'], 'length'); // => { '3': 2, '5': 1 }
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