arrayDiff function Null safety

Array arrayDiff(
  1. Array a
)

Calculate the n-th discrete difference of a Array using the formula out[i] = a[i+1] - a[i].

Parameters

a : input array return a Array with all the differences.

References

  1. "numpy.diff". https://github.com/numpy/numpy/blob/v1.17.0/numpy/lib/function_base.py#L1147-L1275. Retrieved 2019-07-31.
  2. "doc numpy.diff". https://docs.scipy.org/doc/numpy/reference/generated/numpy.diff.html. Retrieved 2019-07-31.
  3. "numpy array indexing". https://docs.scipy.org/doc/numpy/reference/arrays.indexing.html. Retrieved 2019-07-31.

Examples

var a = Array([1, 2, 4, 7, 0]);

print(arrayDiff(a));

/* expected output:
Array([ 1,  2,  3, -7]);
*/

Implementation

Array arrayDiff(Array a) {
  var b = a.getRangeArray(0, a.length - 1);
  var c = a.getRangeArray(1, a.length);

  return c - b;
}