Adding a prefix to each column name in each dataframe in a list of dataframes

Question

I want to add a prefix to each column (except the first) in each dataframe in a list of dataframe. I have been taking the approach that I would used for a single dataframe and trying to use both lapply and Map without success.

I also want change the the first column of each dataframe by adding the name of the dataframe as a prefix to the existing name

A snippet of my list of dataframes

l1 <- list(Fe = structure(list(Determination_No = 1:6, `2` = c(55.94, 
55.7, 56.59, 56.5, 55.98, 55.93), `3` = c(56.83, 56.54, 56.18, 
56.5, 56.51, 56.34), `4` = c(56.39, 56.43, 56.53, 56.31, 56.47, 
56.35), `5` = c(56.32, 56.29, 56.31, 56.32, 56.39, 56.32), `7` = c(56.48, 
56.4, 56.54, 56.43, 56.73, 56.62), `8` = c(56.382, 56.258, 56.442, 
56.258, 56.532, 56.264), `10` = c(56.3, 56.5, 56.2, 56.5, 56.7, 
56.5), `12` = c(56.11, 56.46, 56.1, 56.35, 56.36, 56.37)), class = "data.frame", row.names = c(NA, 
-6L)), SiO2 = structure(list(Determination_No = 1:6, `2` = c(7.63, 
7.65, 7.73, 7.67, 7.67, 7.67), `3` = c(7.84, 7.69, 7.59, 7.77, 
7.74, 7.64), `4` = c(7.67, 7.74, 7.62, 7.81, 7.66, 7.8), `5` = c(7.91, 
7.84, 7.96, 7.87, 7.84, 7.92), `7` = c(7.77, 7.83, 7.76, 7.78, 
7.65, 7.74), `8` = c(7.936, 7.685, 7.863, 7.838, 7.828, 7.767
), `10` = c(7.872684992, 7.851291827, 7.872684992, 7.722932832, 
7.680146501, 7.615967003), `12` = c(7.64, 7.71, 7.71, 7.65, 7.82, 
7.68)), class = "data.frame", row.names = c(NA, -6L)), Al2O3 = structure(list(
    Determination_No = 1:6, `2` = c(2.01, 2.02, 2.03, 2.01, 2.02, 
    2), `3` = c(2.01, 2.01, 2, 2.02, 2.02, 2.03), `4` = c(2, 
    2.03, 1.99, 2.01, 2.01, 2.01), `5` = c(2.02, 2.02, 2.05, 
    2.03, 2.02, 2.03), `7` = c(1.88, 1.9, 1.89, 1.88, 1.88, 1.87
    ), `8` = c(2.053, 2.044, 2.041, 2.038, 2.008, 2.02), `10` = c(2.002830415, 
    2.021725042, 2.021725042, 1.983935789, 2.002830415, 2.021725042
    ), `12` = c(2.09, 2.05, 1.96, 2.09, 2.06, 2.02)), class = "data.frame", row.names = c(NA, 
-6L)))

I have tried the following


colnames(l1[-1]) <- lapply(l1[-1],paste0("Lab-",colnames(l1[-1])))

colnames(l1[-1]) <- Map(paste("Lab",colnames(l1[-1]),sep=" "),l1[-1])

Using either solution I get the following error message

Error in get(as.character(FUN), mode = "function", envir = envir):
  object 'Lab-' of mode 'function' was not found

Ronak Shah · Accepted Answer · 2021-05-06 11:13:38Z

2

In tidyverse, we can use imap with rename_with :

library(dplyr)
library(purrr)

imap(l1, ~.x %>% 
  rename_with(function(x) c(paste(.y, x[1], sep = '_'), paste0('lab_', x[-1]))))

#$Fe
#  Fe_Determination_No lab_2 lab_3 lab_4 lab_5 lab_7  lab_8 lab_10 lab_12
#1                   1 55.94 56.83 56.39 56.32 56.48 56.382   56.3  56.11
#2                   2 55.70 56.54 56.43 56.29 56.40 56.258   56.5  56.46
#3                   3 56.59 56.18 56.53 56.31 56.54 56.442   56.2  56.10
#4                   4 56.50 56.50 56.31 56.32 56.43 56.258   56.5  56.35
#5                   5 55.98 56.51 56.47 56.39 56.73 56.532   56.7  56.36
#6                   6 55.93 56.34 56.35 56.32 56.62 56.264   56.5  56.37

3$SiO2
#  SiO2_Determination_No lab_2 lab_3 lab_4 lab_5 lab_7 lab_8   lab_10 lab_12
#1                     1  7.63  7.84  7.67  7.91  7.77 7.936 7.872685   7.64
#2                     2  7.65  7.69  7.74  7.84  7.83 7.685 7.851292   7.71
#3                     3  7.73  7.59  7.62  7.96  7.76 7.863 7.872685   7.71
#4                     4  7.67  7.77  7.81  7.87  7.78 7.838 7.722933   7.65
#5                     5  7.67  7.74  7.66  7.84  7.65 7.828 7.680147   7.82
#6                     6  7.67  7.64  7.80  7.92  7.74 7.767 7.615967   7.68

#$Al2O3
#  Al2O3_Determination_No lab_2 lab_3 lab_4 lab_5 lab_7 lab_8   lab_10 lab_12
#1                      1  2.01  2.01  2.00  2.02  1.88 2.053 2.002830   2.09
#2                      2  2.02  2.01  2.03  2.02  1.90 2.044 2.021725   2.05
#3                      3  2.03  2.00  1.99  2.05  1.89 2.041 2.021725   1.96
#4                      4  2.01  2.02  2.01  2.03  1.88 2.038 1.983936   2.09
#5                      5  2.02  2.02  2.01  2.02  1.88 2.008 2.002830   2.06
#6                      6  2.00  2.03  2.01  2.03  1.87 2.020 2.021725   2.02

Or in base R with Map :

Map(function(x, y) {
  names(x) <- c(paste(y, names(x)[1], sep = '_'), paste0('lab_', names(x[-1])))
  x
}, l1, names(l1))

answered May 6, 2021 at 11:13

Ronak Shah

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5 Comments

Anoushiravan R Over a year ago

Dear Ronak Shah, I am so sorry to interrupt. May I ask in case I wanted to rename all the columns except the first one why this code returns an error, I just can't spot the problem: l1 %>% map(~ .x %>% rename_with(~ str_c("Lab", names(.x)[-1], sep = "_"), -c(1))) . Thank you very much in advance.

Spooked Over a year ago

@Ronak Shah. Out of curiosity why was my solution for all but the first column not working?

Ronak Shah Over a year ago

@AnoushiravanR You don't need names in rename_with. Try l1 %>% map(~ .x %>% rename_with(~str_c("Lab", ., sep = "_"), -1))

Ronak Shah Over a year ago

@Spooked You cannot do colnames(l1[-1]) <- .... on a list. It would work only on dataframes.

Anoushiravan R Over a year ago

@RonakShah Thank you so much. I really can't thank you enough. It was a subtle point.

jay.sf · Accepted Answer · 2025-05-23 03:57:08Z

Using replace and setNames in lapply.

> lapply(l1, \(x) setNames(x, replace(names(x), -1, paste0('lab_', names(x)[-1]))))
$Fe
  Determination_No lab_2 lab_3 lab_4 lab_5 lab_7  lab_8 lab_10 lab_12
1                1 55.94 56.83 56.39 56.32 56.48 56.382   56.3  56.11
2                2 55.70 56.54 56.43 56.29 56.40 56.258   56.5  56.46
3                3 56.59 56.18 56.53 56.31 56.54 56.442   56.2  56.10
4                4 56.50 56.50 56.31 56.32 56.43 56.258   56.5  56.35
5                5 55.98 56.51 56.47 56.39 56.73 56.532   56.7  56.36
6                6 55.93 56.34 56.35 56.32 56.62 56.264   56.5  56.37

$SiO2
  Determination_No lab_2 lab_3 lab_4 lab_5 lab_7 lab_8   lab_10 lab_12
1                1  7.63  7.84  7.67  7.91  7.77 7.936 7.872685   7.64
2                2  7.65  7.69  7.74  7.84  7.83 7.685 7.851292   7.71
3                3  7.73  7.59  7.62  7.96  7.76 7.863 7.872685   7.71
4                4  7.67  7.77  7.81  7.87  7.78 7.838 7.722933   7.65
5                5  7.67  7.74  7.66  7.84  7.65 7.828 7.680147   7.82
6                6  7.67  7.64  7.80  7.92  7.74 7.767 7.615967   7.68

$Al2O3
  Determination_No lab_2 lab_3 lab_4 lab_5 lab_7 lab_8   lab_10 lab_12
1                1  2.01  2.01  2.00  2.02  1.88 2.053 2.002830   2.09
2                2  2.02  2.01  2.03  2.02  1.90 2.044 2.021725   2.05
3                3  2.03  2.00  1.99  2.05  1.89 2.041 2.021725   1.96
4                4  2.01  2.02  2.01  2.03  1.88 2.038 1.983936   2.09
5                5  2.02  2.02  2.01  2.02  1.88 2.008 2.002830   2.06
6                6  2.00  2.03  2.01  2.03  1.87 2.020 2.021725   2.02

Friede · Accepted Answer · 2025-05-23 09:43:16Z

Similar base R approach using names.

l1 = lapply(l1, \(.) { names(.)[-1] = paste0('lab_', names(.)[-1]); . }) 
# see help('|>')

> l1
$Fe
 Determination_No lab_2 lab_3 lab_4 lab_5 lab_7  lab_8 lab_10 lab_12
1                1 55.94 56.83 56.39 56.32 56.48 56.382   56.3  56.11
2                2 55.70 56.54 56.43 56.29 56.40 56.258   56.5  56.46
3                3 56.59 56.18 56.53 56.31 56.54 56.442   56.2  56.10
4                4 56.50 56.50 56.31 56.32 56.43 56.258   56.5  56.35
5                5 55.98 56.51 56.47 56.39 56.73 56.532   56.7  56.36
6                6 55.93 56.34 56.35 56.32 56.62 56.264   56.5  56.37

$SiO2
 Determination_No lab_2 lab_3 lab_4 lab_5 lab_7 lab_8   lab_10 lab_12
1                1  7.63  7.84  7.67  7.91  7.77 7.936 7.872685   7.64
2                2  7.65  7.69  7.74  7.84  7.83 7.685 7.851292   7.71
3                3  7.73  7.59  7.62  7.96  7.76 7.863 7.872685   7.71
4                4  7.67  7.77  7.81  7.87  7.78 7.838 7.722933   7.65
5                5  7.67  7.74  7.66  7.84  7.65 7.828 7.680147   7.82
6                6  7.67  7.64  7.80  7.92  7.74 7.767 7.615967   7.68

$Al2O3
 Determination_No lab_2 lab_3 lab_4 lab_5 lab_7 lab_8   lab_10 lab_12
1                1  2.01  2.01  2.00  2.02  1.88 2.053 2.002830   2.09
2                2  2.02  2.01  2.03  2.02  1.90 2.044 2.021725   2.05
3                3  2.03  2.00  1.99  2.05  1.89 2.041 2.021725   1.96
4                4  2.01  2.02  2.01  2.03  1.88 2.038 1.983936   2.09
5                5  2.02  2.02  2.01  2.02  1.88 2.008 2.002830   2.06
6                6  2.00  2.03  2.01  2.03  1.87 2.020 2.021725   2.02

Is there a good reason to not rbind in a single data.frame? Explicitly written

l2 =
  do.call(l1, what='rbind') |>
  ( \(.) { names(.)[-1] = paste0('lab_', names(.)[-1]); . } )() |> 
  ( \(.) transform(., formula=sub('\\..*', '', row.names(.))) )() |>
  `row.names<-`(NULL)

> str(l2)
'data.frame':  18 obs. of  10 variables:
$ Determination_No: int  1 2 3 4 5 6 1 2 3 4 ...
$ lab_2           : num  55.9 55.7 56.6 56.5 56 ...
$ lab_3           : num  56.8 56.5 56.2 56.5 56.5 ...
$ lab_4           : num  56.4 56.4 56.5 56.3 56.5 ...
$ lab_5           : num  56.3 56.3 56.3 56.3 56.4 ...
$ lab_7           : num  56.5 56.4 56.5 56.4 56.7 ...
$ lab_8           : num  56.4 56.3 56.4 56.3 56.5 ...
$ lab_10          : num  56.3 56.5 56.2 56.5 56.7 ...
$ lab_12          : num  56.1 56.5 56.1 56.4 56.4 ...
$ formula         : chr  "Fe" "Fe" "Fe" "Fe" ...

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