countBy source npm
_.countBy(collection, [iteratee=_.identity])
Creates an object composed of keys generated from the results of running
each element of collection
through 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).
Arguments
- collection (Array|Object)
The collection to iterate over.
- [iteratee=_.identity] (Function|Object|string)
The function invoked per element.
Returns (Object)
Returns the composed aggregate object.
Example
_.countBy([6.1, 4.2, 6.3], Math.floor);
// => { '4': 1, '6': 2 }
_.countBy(['one', 'two', 'three'], 'length');
// => { '3': 2, '5': 1 }