All possible combinations of a set that sum to a target value

Question

I have an input vector such as:

weights <- seq(0, 1, by = 0.2)

I would like to generate all the combinations of weights (repeats allowed

Answer 1

For the combinations, do you want this:

combinations <- lapply(seq_along(weights), function(x) combn(weights, x))

Then for the sums:

sums <- lapply(combinations, colSums)
inds <- lapply(sums, function(x) which(x == 1))
lapply(seq_along(inds), function(x) combinations[[x]][, inds[[x]]])