tidyfast (version 0.4.0)

dt_count: Count

Description

Count the numbers of observations within groups

Usage

dt_count(dt_, ..., na.rm = FALSE, wt = NULL)

Value

A data.table with counts for each group (or combination of groups)

Arguments

dt_

the data table to uncount

...

groups

na.rm

should any rows with missingness be removed before the count? Default is FALSE.

wt

the wt assigned to the counts (same number of rows as the data)

Examples

library(data.table)
dt <- data.table(
  x = rnorm(1e5),
  y = runif(1e5),
  grp = sample(1L:3L, 1e5, replace = TRUE),
  wt = runif(1e5, 1, 100)
)

dt_count(dt, grp)
dt_count(dt, grp, na.rm = TRUE)
dt_count(dt, grp, na.rm = TRUE, wt = wt)