CODEWITHSUNDEEP
rlistdataframerenameprefix
R.Deilke
R.Deilke

Reputation: 75

How can I put the names of dataframes that are stored in a list into the column names of each dataframe?

Objective: add the dataframe names as prefixes to some columns for a long list of dataframes

Problem: Using lapply or loops it seems like R doesn't pass the name of the dataframes to the method.

Data:

A<-data.frame(column_1=c(1,2,3),column_2=c(4,5,6),column_3=c(7,8,9),column_4=c(10,11,12))
B<-data.frame(column_1=c(13,14,15),column_2=c(16,17,18),column_3=c(19,20,21),column_4=c(22,23,24))
C<-data.frame(column_1=c(25,26,27),column_2=c(28,29,30),column_3=c(31,32,33),column_4=c(34,35,36))
list_of_dataframes<-list(A,B,C)
names(list_of_dataframes)<-c("A","B","C")

This is just an example. Actually my list of dataframes is quite long. So, it comes unhandy to add names manually with 'comment' like it is done here.

Desired Solution:

$A
  A_column_1 A_column_2 A_column_3 column_4
1          1          4          7       10
2          2          5          8       11
3          3          6          9       12

$B
  B_column_1 B_column_2 B_column_3 column_4
1         13         16         19       22
2         14         17         20       23
3         15         18         21       24

$C
  C_column_1 C_column_2 C_column_3 column_4
1         25         28         31       34
2         26         29         32       35
3         27         30         33       36

As you can see the dataframe names are in the column names, except for column 4 which I want to exclude from this operation.

My Try:

The desired solution was actually produced by some code:

comment(list_of_dataframes$A) <- "A"
comment(list_of_dataframes$B) <- "B"
comment(list_of_dataframes$C) <- "C"


list_of_dataframes<-lapply(list_of_dataframes,function(dataframe){

  a<-comment(dataframe)


  colnames(dataframe)[c(1,2,3)]<-paste(a, colnames(dataframe)[c(1,2,3)], sep = "_") 

  return(dataframe)


}
)

list_of_dataframes

The problem with this solution is that I actually have a very long list of dataframes and I have many of such lists. So, I need to do all of this in an automated fashion. In the above code I use 'comment' where I separately type in the name of each dataframe. I need instead to automatically take the name of each dataframe. How can I do this?

I tried to use deparse(substitute(dataframe)) as here:

list_of_dataframes<-lapply(list_of_dataframes,function(dataframe){

  a<-deparse(substitute(dataframe))


  colnames(dataframe)<-paste(a, colnames(dataframe), sep = "_") 

  return(dataframe)


}
)

But, as you can see the names of the dataframe don't seem to be passed to lapply:

$A
  X[[i]]_column_1 X[[i]]_column_2 X[[i]]_column_3 X[[i]]_column_4
1               1               4               7              10
2               2               5               8              11
3               3               6               9              12

$B
  X[[i]]_column_1 X[[i]]_column_2 X[[i]]_column_3 X[[i]]_column_4
1              13              16              19              22
2              14              17              20              23
3              15              18              21              24

$C
  X[[i]]_column_1 X[[i]]_column_2 X[[i]]_column_3 X[[i]]_column_4
1              25              28              31              34
2              26              29              32              35
3              27              30              33              36

Do you have any ideas how I can overcome this problem?

Upvotes: 3

Views: 120

Answers (2)

akrun
akrun

Reputation: 887971

We can also use str_c

library(dplyr)
library(purrr)
imap(list_of_dataframes, ~ {
            nm1 <- .y
            .x %>% rename_at(1:3, ~ str_c(nm1, ., sep="_"))
        })

Upvotes: 0

Ronak Shah
Ronak Shah

Reputation: 389325

In base R, you can do : 

Map(function(x, y) {names(x)[1:3] = paste(y, names(x)[1:3], sep = "_");x}, 
                   list_of_dataframes, names(list_of_dataframes))

Or using imap from purrr

library(dplyr)
purrr::imap(list_of_dataframes, 
             ~.x %>% rename_at(1:3, function(x) paste(.y, x, sep = "_")))


#$A
#  A_column_1 A_column_2 A_column_3 column_4
#1          1          4          7       10
#2          2          5          8       11
#3          3          6          9       12

#$B
#  B_column_1 B_column_2 B_column_3 column_4
#1         13         16         19       22
#2         14         17         20       23
#3         15         18         21       24

#$C
#  C_column_1 C_column_2 C_column_3 column_4
#1         25         28         31       34
#2         26         29         32       35
#3         27         30         33       36

Upvotes: 2

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