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Safely Rename Data Frames

Stu Field

tips-safely-rename-df.Rmd

Introduction

Renaming variables/features of a data frame (or tibble) is a common task in data science. Doing so safely is often a struggle. This can be achieved safely via the dplyr::rename() function via 2 steps:

  1. Set up the mapping in either a named vector
  2. Apply the dplyr::rename() function via !!! syntax
  3. Alternatively, roll-your-own rename() function
  • Note: all entries in the mapping (i.e. key) object must be present as names in the data frame object.

Example with mtcars 

# Create map/key of the names to map
key <- c(MPG = "mpg", CARB = "carb")   # named vector
key
#>    MPG   CARB 
#>  "mpg" "carb"

# rename `mtcars`
rename(mtcars, !!! key) |> head()
#>                    MPG cyl disp  hp drat    wt  qsec vs am gear CARB
#> Mazda RX4         21.0   6  160 110 3.90 2.620 16.46  0  1    4    4
#> Mazda RX4 Wag     21.0   6  160 110 3.90 2.875 17.02  0  1    4    4
#> Datsun 710        22.8   4  108  93 3.85 2.320 18.61  1  1    4    1
#> Hornet 4 Drive    21.4   6  258 110 3.08 3.215 19.44  1  0    3    1
#> Hornet Sportabout 18.7   8  360 175 3.15 3.440 17.02  0  0    3    2
#> Valiant           18.1   6  225 105 2.76 3.460 20.22  1  0    3    1

Alternative to dplyr

If you prefer to avoid the dplyr import/dependency, you can achieve a similar result with similar syntax by writing your own renaming function:

rename2 <- function (.data, ...) {
  map <- c(...)
  loc <- setNames(match(map, names(.data), nomatch = 0L), names(map))
  loc <- loc[loc > 0L]
  newnames <- names(.data)
  newnames[loc] <- names(loc)
  setNames(.data, newnames)
}

Now, with similar syntax (but cannot use !!!):

# rename `mtcars` in-line
rename2(mtcars, MPG = "mpg", CARB = "carb") |>
  head()
#>                    MPG cyl disp  hp drat    wt  qsec vs am gear CARB
#> Mazda RX4         21.0   6  160 110 3.90 2.620 16.46  0  1    4    4
#> Mazda RX4 Wag     21.0   6  160 110 3.90 2.875 17.02  0  1    4    4
#> Datsun 710        22.8   4  108  93 3.85 2.320 18.61  1  1    4    1
#> Hornet 4 Drive    21.4   6  258 110 3.08 3.215 19.44  1  0    3    1
#> Hornet Sportabout 18.7   8  360 175 3.15 3.440 17.02  0  0    3    2
#> Valiant           18.1   6  225 105 2.76 3.460 20.22  1  0    3    1

# rename `mtcars` via named `key`
rename2(mtcars, key) |>
  head()
#>                    MPG cyl disp  hp drat    wt  qsec vs am gear CARB
#> Mazda RX4         21.0   6  160 110 3.90 2.620 16.46  0  1    4    4
#> Mazda RX4 Wag     21.0   6  160 110 3.90 2.875 17.02  0  1    4    4
#> Datsun 710        22.8   4  108  93 3.85 2.320 18.61  1  1    4    1
#> Hornet 4 Drive    21.4   6  258 110 3.08 3.215 19.44  1  0    3    1
#> Hornet Sportabout 18.7   8  360 175 3.15 3.440 17.02  0  0    3    2
#> Valiant           18.1   6  225 105 2.76 3.460 20.22  1  0    3    1