R subsetting a data.table by values of a character variable-CodePudding

I'm attempting to subset a data.table, small example here but will need to do bigger one.

I have the dt and the only column, code_id is the key:

> UniqueCodes
                 code_id
    1:                  
    2:             .....
    3: 10073011000001107
    4: 10073911000001106
    5: 10075611000001101
   ---                  
15114:             x05ZX
15115:             x05q2
15116:             x05qb
15117:             x05td
15118:             x05xd

I have long list of codes I want to retain (subset) and discard the rest. So how would I subset this df and retain only x05ZX, X05qb, and X05td ? I know apriory these are the only ones I want to keep ? Thx, J.

CodePudding user response：

library(data.table)

code_id <- c(10073011000001107,
             10073911000001106,
             10075611000001101,
             "x05ZX",
             "x05q2",
             "x05qb",
             "x05td",
             "x05xd",
             "x05qb")

UniqueCodes <- data.table(code_id)

You can build a vector with the codes you want to retain

codes <- c("x05ZX", "X05qb", "X05td", "x05qb")

Then pass the vector to dt

UniqueCodes[code_id %in% codes]
##  code_id
## 1:   x05ZX
## 2:   x05qb
## 3:   x05qb