R append dataframe name to each of its columns within a list of dataframes

Question

I want to append the dataframe-name to each of its columns in the following list of dataframes:

df1 <- tibble(V1=c(1, 1, 3, 1),
                V2=c(2, 1, 2, 2),
                V3=c(4, 1, 1, 2))
df2 <- tibble(V1=c(1, 1, 3, 1),
                V2=c(2, 1, 2, 2),
                V3=c(4, 1, 1, 2))
df <- list(df1, df2)
names(df) <- c("df1", "df2")
df

This is how I would like it to look:

$df1
# A tibble: 4 x 3
  df1_V1 df1_V2 df1_V3
   <dbl>  <dbl>  <dbl>
1      1      2      4
2      1      1      1
3      3      2      1
4      1      2      2

$df2
# A tibble: 4 x 3
  df2_V1 df2_V2 df2_V3
   <dbl>  <dbl>  <dbl>
1      1      2      4
2      1      1      1
3      3      2      1
4      1      2      2

I have tried:

    appendDFnameToColumns <- function(df, prefix = "", sep = "") {
      colnames(df) <- paste(prefix, colnames(df), sep = sep) 
      df
      }
    
    df <- map(df, appendDFnameToColumns, 
                             prefix = names(df$.),
                             sep ="_")

Thanks in advance

iago · Accepted Answer · 2020-10-27 12:03:31Z

3

With purrr:

library(tidyverse)
names(df) %>% 
    map(function(dtf) {get(dtf) %>% rename_with(~paste0(dtf,"_",.))})
[[1]]
# A tibble: 4 x 3
  df1_V1 df1_V2 df1_V3
   <dbl>  <dbl>  <dbl>
1      1      2      4
2      1      1      1
3      3      2      1
4      1      2      2

[[2]]
# A tibble: 4 x 3
  df2_V1 df2_V2 df2_V3
   <dbl>  <dbl>  <dbl>
1      1      2      4
2      1      1      1
3      3      2      1
4      1      2      2

answered Oct 27, 2020 at 12:03

iago

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Comments

Ronak Shah · Accepted Answer · 2020-10-27 12:03:41Z

2

A tidyverse approach with purrrs imap :

library(dplyr)
library(purrr)

imap(df,~rename_with(.x, function(x) paste(.y, x, sep = '_')))

#$df1
# A tibble: 4 x 3
#  df1_V1 df1_V2 df1_V3
#   <dbl>  <dbl>  <dbl>
#1      1      2      4
#2      1      1      1
#3      3      2      1
#4      1      2      2

#$df2
# A tibble: 4 x 3
#  df2_V1 df2_V2 df2_V3
#   <dbl>  <dbl>  <dbl>
#1      1      2      4
#2      1      1      1
#3      3      2      1
#4      1      2      2

Or in base R you can use Map :

Map(function(x, y) setNames(x, paste(y, names(x), sep = '_')), df, names(df))

answered Oct 27, 2020 at 12:03

Ronak Shah

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Comments

akrun · Accepted Answer · 2020-10-27 23:03:34Z

1

We can use rename with !!!

library(dplyr)
library(purrr)
library(stringr)
map2(df, names(df), ~ .x %>% 
       rename(!!! setNames(names(.), str_c(.y, names(.), sep="_"))))

-output

#$df1
# A tibble: 4 x 3
#  df1_V1 df1_V2 df1_V3
#   <dbl>  <dbl>  <dbl>
#1      1      2      4
#2      1      1      1
#3      3      2      1
#4      1      2      2

#$df2
# A tibble: 4 x 3
#  df2_V1 df2_V2 df2_V3
#   <dbl>  <dbl>  <dbl>
#1      1      2      4
#2      1      1      1
#3      3      2      1
#4      1      2      2

answered Oct 27, 2020 at 23:03

akrun

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