CODEWITHSUNDEEP
rdplyrrlangtidyeval
Indrajeet Patil
Indrajeet Patil

Reputation: 4889

using rlang to select the entire dataframe and not just one column

I am trying to create a custom function where some operation is carried out only on one column of the dataframe. But I want the function to work in such a way that it will output not only the column on which the operation was carried out, but also the entire dataframe from which that particular column was drawn. This is a very simple example of what I want to achieve:

# libraries needed
library(dplyr)
library(rlang)

# creating a dataframe
data <-
  as.data.frame(cbind(
    x = rnorm(5),
    y = rnorm(5),
    z = rnorm(5)
  ))

# defining the custom function
custom.fn <- function(data, x) {
  df <- dplyr::select(.data = data,
                      x = !!rlang::enquo(x)) # how can I also retain all the other columns in the dataframe apart from x?
  df$x <- df$x / 2
  return(df)
}

# calling the function (also want y and z here in the ouput)
custom.fn(data = data, x = x)
#>             x
#> 1  0.49917536
#> 2 -0.03373202
#> 3 -1.24845349
#> 4 -0.15809688
#> 5  0.11237030

Created on 2018-02-14 by the reprex package (v0.1.1.9000).

Upvotes: 2

Views: 293

Answers (1)

C. Braun
C. Braun

Reputation: 5211

Just specify the columns you want to include in your select call:

custom.fn <- function(data, x) {
  df <- dplyr::select(.data = data,
                      x = !!rlang::enquo(x), y, z)
  df$x <- df$x / 2
  return(df)
}

If you don't want to name the rest of the columns explicitly, you can also use everything:

df <- dplyr::select(.data = data, x = !!rlang::enquo(x), dplyr::everything())

Upvotes: 2

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