slice_head: Select first or last rows

In vectra: Columnar Query Engine for Larger-than-RAM Data

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)

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.

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.

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)

vectra documentation built on May 8, 2026, 9:06 a.m.