Fast and simple "Min/max" sub-sampling of a (possibly segmented) list coercible to a two-dimensional (X/Y) chart of double-s.
Create an instance of this class by passing your List<List<T>> and a ILSTransformer<T> of your type T to the constructor.
Null elements are not permitted.
Input list(s) are assumed to be sorted by X-values in ascending order!
Original list had about 10 000 points. Chart width is about 1000 pixels.
(10 points per bucket, thus the subsampled list is about 10x smaller)
(100 points per bucket, thus the subsampled list is about 100x smaller)
(1000 points per bucket, thus the subsampled list is about 1000x smaller)
Complexity of the algorithm is just O(n).
Proceeding through the input data, elements are being divided into buckets (by X-value). For each bucket a minimum element and a maximum element (by Y-value) is found, and added to the output (in their original X-order).
Two input segments will be merged in the output unless they are separated by more than the bucket size.
Add the following line to your build.gradle file:
implementation 'com.github.Sublimis:ListSubsample:3.0'You can find more info at https://jitpack.io/#Sublimis/ListSubsample.
final List<List<T>> inputData = ...; // Your data with elements of type T
final double bucketSize = 10; // Adjust the bucket size according to your needs
final List<List<T>> sample = new ListSubsample<T>(inputData,
new ILSTransformer<T>()
{
@Override
public double getX(final T entry)
{
return entry.getX();
}
@Override
public double getY(final T entry)
{
return entry.getY();
}
})
.getSubsample(bucketSize);