Question

I need a function like Matlab’s trimmean() in Java, and I do not want to reinvent the wheel.

Anybody is aware of a ready implementation for that? (Yes, I know I can make it in no time but I wouldn’t waste time on it if someone already contributed it to the community.)

I Googled for some alternatives but I only found partial and placeholder implementations (like this or this).

Any suggestion is more than appreciated, the best would be a Maven dependency I can go play with.

Thanks in advance!

Answer 1

Just for the archives, I found an acceptable solution with Colt:

public static void trimmean(final double[] arr, final int percent) {
    if ( percent < 0 || 100 < percent ) {
        throw new IllegalArgumentException("Unexpected value: " + percent);
    }

    if ( 0 == arr.length ) {
        return Double.NaN;
    }

    final int n = arr.length;
    final int k = Math.round(n * ( percent / 100.0 ) / 2.0); // Check overflow
    final DoubleArrayList list = new DoubleArrayList( arr );
    list.sort();
    
    return Descriptive.winsorizedMean( list, Descriptive.mean( list ), k, k );
}