How to count unique elements in Arraylist?

Programming Questions

lunchboxav

How to count unique elements in Arraylist?

in Programming Questions • 2 years ago

Hi there guys :D

Is there anyway to count unique element in arraylist? I have a number of elements inside an arraylist and I want to count the frequency of each element's appearance. I understand that there's a method such as frequency for Java, but I don't know how to do this natively in Processing.

Thanks for your help :D
Cheers

Replies(1)

PhiLho

Re: How to count unique elements in Arraylist?

2 years ago

That's a rather common question (at least I answered it a couple of times...).
A common technique is to use a HashMap, with the element as key, and the number of occurrences as value: get the value. If null, create an entry with a value of 1. Otherwise, increment the value and store it again in the map.

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