Given a set of values and a grouped vector x, find parallel matches of each value in the different groups and return their positions in the original vector x. If there are multiple matches of the same value in a group, only the position of the first match is returned.
match.split(x, f, values=NULL, groups=NULL, nomatch=NA_integer_)
An integer matrix with one row for each value (in values) and one column for each group (in groups), specifying the index in x of the first match of a value within the respective group. If not match is found for a given combination of value and group, nomatch is inserted (defaults to NA).
vector to be divided into groups and matched against
a factor that defines the grouping (or a vector that can be converted to a factor)
values to be matched in x.
Defaults to values that occur in all groups of x as determined by f and groups
a character vector listing the set of groups to be formed. Defaults to the levels of f and should be a subset of these levels if given explicitly
the value to be returned in cases where no match is found (coerced to an integer)
Stephanie Evert (https://purl.org/stephanie.evert)