CODEWITHSUNDEEP
r
Vasile
Vasile

Reputation: 1017

assign names to data frames columns in a list

I have a list of data frames

# Create dummy data
df1<-data.frame( c(1,2,3),c(2,3,4))
df2<-data.frame(c(5,6,7),c(4,5,6))

# Create a list
l<-list(df1, df2)

I would like to assign names to columns. As l[[1]][,1] gives me access to the first column, I thought I could assign 'names' as the first column name by:

l<-lapply(l, function(x)names(x[[1]][,1]<-"names"))

But this gives me an error

Error in x[[1]][, 1] <- "names" : 
  incorrect number of subscripts on matrix

Edit: Added some dput initial data

dput(lapply(head(results1, 2), head, 2))
list(structure(c(1.27679607834331, 1.05090175857491), .Dim = 2:1, .Dimnames = list(
    c("..a15.pdf", "..a17.pdf"), "x")), structure(c(2.096687569578, 
2.19826038300833), .Dim = 2:1, .Dimnames = list(c("..a15.pdf", 
"..a17.pdf"), "x")))

after trying to assign the name

dput(lapply(head(results1, 2), head, 2))
list(structure(c(1.27679607834331, 1.05090175857491), .Dim = 2:1, .Dimnames = list(
    c("..a15.pdf", "..a17.pdf"), "names")), structure(c(2.096687569578, 
2.19826038300833), .Dim = 2:1, .Dimnames = list(c("..a15.pdf", 
"..a17.pdf"), "names")))

Output:

results1[1]
[[1]]
                       names
..a15.pdf         1.27679608
..a17.pdf         1.05090176
..a18.pdf         1.51820192
..a21.pdf         2.30296037
..a2TTT.pdf       1.48568732

Upvotes: 0

Views: 370

Answers (1)

Ronak Shah
Ronak Shah

Reputation: 389325

You can subset the names of the dataframe:

l <- lapply(l, function(x) {names(x)[1] <-"names";x})
l

In tidyverse -

library(dplyr)
library(purrr)

l <- map(l, ~.x %>% rename_with(~'names', 1))

From the updated data it seems you have list of matrices and the first column is actually rowname which you can convert to a column and name it.

lapply(results1, function(x) {
  mat <- cbind.data.frame(names = rownames(x), x)
  rownames(mat) <- NULL
  mat
})

#[[1]]
#      names    x
#1 ..a15.pdf 1.28
#2 ..a17.pdf 1.05

#[[2]]
#      names   x
#1 ..a15.pdf 2.1
#2 ..a17.pdf 2.2

Upvotes: 2

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