vectra (version 0.6.2)

slice_head: Select first or last rows

Description

Select first or last rows

Usage

slice_head(.data, n = 1L)
slice_tail(.data, n = 1L)
slice_min(.data, order_by, n = 1L, with_ties = TRUE)
slice_max(.data, order_by, n = 1L, with_ties = TRUE)

Value

A vectra_node for slice_head() and slice_min/max(..., with_ties = FALSE). A data.frame for slice_tail() and slice_min/max(..., with_ties = TRUE) (the default), since these must materialize all rows.

Arguments

.data

A vectra_node object.

n

Number of rows to select.

order_by

Column to order by (for slice_min/slice_max).

with_ties

If TRUE (default), includes all rows that tie with the nth value. If FALSE, returns exactly n rows.

Examples

f <- tempfile(fileext = ".vtr")
write_vtr(mtcars, f)
tbl(f) |> slice_head(n = 3) |> collect()
tbl(f) |> slice_min(order_by = mpg, n = 3) |> collect()
tbl(f) |> slice_max(order_by = mpg, n = 3) |> collect()
unlink(f)