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package org.rcsb.mmtf.encoder;

import java.util.ArrayList;
import java.util.List;

import org.rcsb.mmtf.utils.CodecUtils;

/**
 * A class of methods to encode arrays.
 * e.g. using delta encoding.
 * @author Anthony Bradley
 *
 */
public class ArrayEncoders {

	/**
	 * Delta encode an array of integers.
	 * @param intArray the input array
	 * @return the encoded array
	 */
	public static int[] deltaEncode(int[] intArray) {
		int[] out = new int[intArray.length];
		System.arraycopy(intArray, 0, out, 0, intArray.length);
		for (int i = out.length-1; i > 0; i--) {
			out[i] = out[i] - out[i-1];
		}
		return out;
	}

	/**
	 * Run length encode an array of integers.
	 * @param intArray the input array
	 * @return the encoded integer array
	 */
	public static int[] runlengthEncode(int[] intArray) {
		// If it's length zero
		if (intArray.length==0){
			return new int[0];
		}
		// We don't know the length so use
		List outList = new ArrayList<>();
		int lastInt = intArray[0];
		int counter = 1;
		for (int i=1; i