R data.table：将日期 (01) 添加到日期的有效方法

Question

I have the following data.table :

library(data.table)
DT <- data.table(n = c("A", "B"), dt_start = c("10/2020", "05/2015"))

I want:

DT <- data.table(n = c("A", "B"), dt_start = c("2020-10-01", "2015-05-01"))

Answer 1

You can use paste0 to add the day to the character and use as.Date to coerce it:

DT[, dt_start := as.Date(paste0("01/", DT$dt_start), "%d/%m/%Y")]

The result is

DT
   n   dt_start
1: A 2020-10-01
2: B 2015-05-01