statar (version 0.1.3)

setmutate: Version of mutate that (i) transforms data.table in place (ii) allows by, i condition

Description

Version of mutate that (i) transforms data.table in place (ii) allows by, i condition

Usage

setmutate(x, ..., i = NULL, by = NULL)
setmutate_(x, vars, i = NULL, by = NULL)

Arguments

x

a data.table

...

Variables to include. Defaults to all non-grouping variables.

i

a condition that restricts the set of row on which to apply the function

by

Groups within which the function should be applied

vars

Used to work around non-standard evaluation.

Examples

library(data.table)
library(dplyr)
N <- 100
DT <- data.table(
  id = sample(5, N, TRUE),
  v1 = sample(5, N, TRUE),
  v2 = sample(1e6, N, TRUE)
)
setmutate(DT, mean(v2), by = v1)
setmutate_(DT, setNames("mean(v2)", "v3"), by = "v1")
setmutate_(DT, setNames("mean(v2)", "v3"), i = "id==1", by = "v1")