Weighted random selection from array

Question

I would like to randomly select one element from an array, but each element has a known probability of selection.

All chances together (within the array) sums to 1.<

Answer 1

If the array is small, I would give the array a length of, in this case, five and assign the values as appropriate:

array[
    0 => 0
    1 => 0
    2 => 0
    3 => 0
    4 => 1
]