Renaming columns in the global environment

Question

I have these data frames in R within the global environment:

file_1 <- data.frame(id = 1:5, samplecolumn = letters[1:5], value = rnorm(5))
file_2 <- data.frame(id = 1:5, sample_column = letters[6:10], value = rnorm(5))
file_3 <- data.frame(id = 1:5, othercolumn = letters[11:15], value = rnorm(5))
abc_1 <- data.frame(id = 1:5, samplecolumn = letters[16:20], value = rnorm(5))

For all data frames starting with "file_", if there is a column the name "samplecolumn", I want to rename it as "sample_column".

I thought that I could do this by first identifying all data frames starting with "file_", and then renaming them:

all_objects <- ls()

file_objects <- all_objects[grep("^file_", all_objects)]

for (file in file_objects) {
    df <- get(file)
    
    if ("samplecolumn" %in% colnames(df)) {
        colnames(df)[colnames(df) == "samplecolumn"] <- "sample_column"
        
        assign(file, df)
    }
}

Is this the correct way to do this in R?

Answer 1

Here is a base R way. Get the data frames with ls/mget, then lapply a function making the changes.

ls(pattern = "file_") |>
  mget() |>
  lapply(\(x) {
    names(x) <- ifelse(grepl("samplecolumn", names(x)), "sample_column", names(x))
    x
  })
#> $file_1
#>   id sample_column      value
#> 1  1             a  0.3567935
#> 2  2             b  0.1467364
#> 3  3             c  0.2088358
#> 4  4             d  1.9435469
#> 5  5             e -1.6413247
#> 
#> $file_2
#>   id sample_column      value
#> 1  1             f -0.2842375
#> 2  2             g  0.5040112
#> 3  3             h  2.5262186
#> 4  4             i  0.5083768
#> 5  5             j  0.7501698
#> 
#> $file_3
#>   id othercolumn       value
#> 1  1           k -0.17416173
#> 2  2           l -0.04321274
#> 3  3           m -0.16325477
#> 4  4           n -0.53594218
#> 5  5           o  1.11494155

^{Created on 2024-09-28 with reprex v2.1.0}

Or, more simple, with setNames.

ls(pattern = "file_") |>
  mget() |>
  lapply(\(x) 
         setNames(x, ifelse(grepl("samplecolumn", names(x)), "sample_column", names(x)))
  )
#> $file_1
#>   id sample_column      value
#> 1  1             a  1.5820405
#> 2  2             b -0.6436687
#> 3  3             c -0.5669997
#> 4  4             d  0.9622013
#> 5  5             e -0.9325018
#> 
#> $file_2
#>   id sample_column      value
#> 1  1             f -0.3382037
#> 2  2             g  0.3404972
#> 3  3             h  0.2350941
#> 4  4             i -0.1942233
#> 5  5             j  0.7478564
#> 
#> $file_3
#>   id othercolumn      value
#> 1  1           k  2.3387201
#> 2  2           l -1.0179311
#> 3  3           m  0.3301583
#> 4  4           n -0.3459007
#> 5  5           o  2.2805970

^{Created on 2024-09-28 with reprex v2.1.0}