key.sum: Function summing by a given key
In barryrowlingson/opVaR: Computes operational risk

Description Usage Arguments Value Note See Also Examples

Sums elements of a given vector by a given key.

1	key.sum(v, u)

`v`	vector to be summed
`u`	vector of non-negative integers indicating how values of `v` should be summed

A vector obtained by summing values of v by the key u.

It is intended that: length(v) != sum(u) but otherwise function computes its value vector as well.

function key.sum is part of function period.loss

# the first example:

v <- c(0,1,2,3.4,2)
u <- c(2,2,0,1)

key.sum(v,u)

# the second example:

v1 <- c(0,1,2,3.4,2)
u1 <- c(2,2,0)

key.sum(v1,u1) # of course there is not enough u data to have v1[5] accounted in the value vector

# the third example:

v2 <- c(0,1,2,3.4)
u2 <- c(2,2,0,1)

key.sum(v2,u2) # of course there is not enough v2 data to sum by u2