Declare which column an aniframe is indexed by

Changing the index changes the order the rows come in, so — like the variables_* declarations — it is not reachable through set_metadata() and has its own setter, which does the restructuring too.

Usage

set_index(data, column)

Arguments

data

An aniframe object.

column

Length-one character vector naming the index column. It must exist in data and be numeric.

Value

data, re-indexed and restructured.

Details

If the column was declared as temporal context it stops being so: a variable cannot be both the position within a context and part of it. The column the frame was previously indexed by becomes an ordinary undeclared column rather than being promoted to a grouping variable — which, holding one value per row, would put every row in its own group.

See also

get_index()

Examples

df <- data.frame(frame = 1:3, individual = "a", x = c(1, 2, 3), y = c(0, 1, 0))
af <- as_aniframe(df, index = "frame")
get_index(af)
#> [1] "frame"