Skip to contents

Fast counting via dtplyr

fastcount.Rd

`fastcount()` delegates [dplyr::count()] to a `data.table` backend by converting the input to a lazy `dtplyr` table first. This preserves the familiar `count()` interface while exploiting `data.table` performance.

Usage

fastcount(x, ..., wt = NULL, sort = FALSE, name = NULL)

Arguments

x

A data frame, data frame extension (e.g. a tibble), or a lazy data frame (e.g. from dbplyr or dtplyr).

...

<data-masking> Variables to group by.

wt

<data-masking> Frequency weights. Can be NULL or a variable:

  • If NULL (the default), counts the number of rows in each group.

  • If a variable, computes sum(wt) for each group.

sort

If TRUE, will show the largest groups at the top.

name

The name of the new column in the output.

If omitted, it will default to n. If there's already a column called n, it will use nn. If there's a column called n and nn, it'll use nnn, and so on, adding ns until it gets a new name.

Value

A tibble with one row per group and a count column.

Examples

df <- tibble::tibble(group = c("a", "a", "b"))
fastcount(df, group)
#> # A tibble: 2 × 2
#>   group     n
#>   <chr> <int>
#> 1 a         2
#> 2 b         1