make_fromids {hydroloom}

Convert "to" index ids to "from" index ids

Description

given a set of index ids as retrieved from make_index_ids return an adjacency matrix with pointers to identifiers that flow to the row of the matrix in question.

Usage

make_fromids(index_ids, return_list = FALSE)

Arguments

index_ids

data.frame as returned by make_index_ids

return_list

logical if TRUE, the returned list will include a "froms_list" element containing all from ids in a list form.

Value

list containing a "froms" matrix, "lengths" vector, and optionally "froms_list" elements.

Examples

x <- data.frame(id = c(1, 2, 3, 4, 5, 6, 7, 8, 9),
              toid = c(2, 3, 4, 5, 0, 7, 8, 9, 4))

y <- make_index_ids(x)

make_fromids(y)