I'm writing a range to select a random sampling of a forward range. The
number of elements in the forward range is already known.
The strategy is: at any moment, I know I need to select k random samples
out of n. To implement popFront, I generate a random number in [0, n -
k]. That's the probability that the next item in the input will be part
of the selection. If the random number is 0, then the element got
selected. Otherwise, I must ignore that guy so I popFront the input
range, decrease n by one, and repeat.
This seems reasonable but somehow the selection comes skewed: the
elements towards the beginning of the range are less represented than
the ones towards the end. Where am I wrong?
Andrei
- randomSample Andrei Alexandrescu
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