How do I extract the values of my data that constitute a certain percentile?

I have been using the 'prctile' function in MATLAB R2017b to find certain percentiles of my data. I am wondering if there is a way to automatically return the values that constitute these percentiles.

For example, I am getting the 10th, 20th and 30th percentiles of my data by the following line:

>> p10 = prctile(data, [10 20 30]);

How can I extract the values of 'data' that are in each of these percentiles?

Answer 1

[MathWorks Support Team]

The 'prctile' function does not provide an automatic way to extract the values of your data that constitute a certain percentile. However, you can use 'prctile' along with another couple lines of code to obtain these values. Below are a couple examples:

Method 1:

>> m = rand(1, 20); % generate a random list of numbers
>> percentiles = prctile(m, [10 20 30]); 
>> vals10 = m(m <= percentiles(1)); % values in the 10th percentile
>> vals20 = m(m <= percentiles(2)); % values in the 20th percentile
>> vals30 = m(m <= percentiles(3)); % values in the 30th percentiles

Method 2:

>> m = rand(1, 20);
>> mSorted = sort(m); 
>> vals10 = mSorted(1:floor(end * 0.1)); 
>> vals20 = mSorted(1:floor(end * 0.2));
>> vals30 = mSorted(1:floor(end * 0.3));

Note: Method 2 does not calculate the percentiles, just the values that constitute each percentile. It also does not keep the data in its original order.