select a row index weighted by value

weight dictionary: {1:0.1, 2:0.9} (there is a 10% probability of an item with the value 1 of being selected, 90% with value 2)

exmple value row: [0, 0, 1, 0, 2, 1] (the will only be 0s and values that are contained in the dictionary)

The output should be a randomly chosen index

For the example row, the probabilities of the index of being selected for each item in the row should be [0, 0, 0.05, 0, 0.9, 0.05] (note that since the row contains two different 1 elements, each of them should have a prob of 0.05 of being selected, since the weight counts towards an item with that value being selected)