data.table alternative for dplyr mutate_? - r

Question

I have following r code which uses dplyr.
Due to large data size, we want to use data.table.
test <- function(Act, mac, type, thisYear){
Act %>%
mutate_(var = type) %>%
filter(var == mac) %>%
filter(floor_date(as.Date(submit_ts), 'year') == thisYear)
}
Act is as follows
| submit_ts | col1 | col2 |
| ------------- |---------------|-------|
| '2015-01-01' | 'x' | 1000 |
| '2015-01-01' | 'y' | 200 |
| '2015-01-01' | 'x' | 200 |
basically function can works as follows
test(act, 'x', 'col1', 2015)
result is as follows
| submit_ts | col1 | col2 |
| ------------- |---------------|-------|
| '2015-01-01' | 'x' | 1000 |
| '2015-01-01' | 'x' | 200 |
test(act, 200, 'col2', 2015)
result is as follows
| submit_ts | col1 | col2 |
| ------------- |---------------|-------|
| '2015-01-01' | 'y' | 200 |
| '2015-01-01' | 'x' | 200 |
How should I do it using data.table ?

Answer 1

We can do a similar approach in data.table with
library(data.table)
library(lubridate)
test1 <- function(Act, mac, type){
setnames(setDT(Act), type, "var")[
var==mac & year(floor_date(as.Date(submit_ts), "year"))==thisYear]
}
test1(dat, 2, "val")
# submit_ts var
#1: 2013-05-05 2
#2: 2013-05-12 2
NOTE: The floor_date does not return a yyyy year.
data
dat <- data.frame(submit_ts= c("2013-05-05", "2012-05-10", "2013-05-12"),
val = c(2, 1, 2), stringsAsFactors=FALSE)
thisYear <- 2013