Summarise grouped data

Usage

summarise(.data, ..., .groups = NULL)

summarize(.data, ..., .groups = NULL)

Arguments

.data: A grouped vectra_node (from group_by()).
...: Named aggregation expressions using n(), sum(), mean(), min(), max(), sd(), var(), first(), last(), any(), all(), median(), n_distinct().
.groups: How to handle groups in the result. One of "drop_last" (default), "drop", or "keep".

Value

A vectra_node with one row per group.

Details

Aggregation is hash-based by default. When the engine detects it is advantageous, it switches to a sort-based path that can spill to disk, keeping memory bounded regardless of group count.

All aggregation functions accept na.rm = TRUE to skip NA values. Without na.rm, any NA in a group poisons the result (returns NA). R-matching edge cases: sum(na.rm = TRUE) on all-NA returns 0, mean(na.rm = TRUE) on all-NA returns NaN, min/max(na.rm = TRUE) on all-NA returns Inf/-Inf with a warning.

This is a materializing operation.

Examples

f <- tempfile(fileext = ".vtr")
write_vtr(mtcars, f)
tbl(f) |> group_by(cyl) |> summarise(avg_mpg = mean(mpg)) |> collect()
unlink(f)