CODEWITHSUNDEEP
r
user2806363
user2806363

Reputation: 2593

How to remove duplicated column names in R?

I have very big matrix, I know that some of the colnames of them are duplicated. so I just want to find those duplicated colnames and remove on of the column from duplicate. I tried duplicate(), but it removes the duplicate entries. Would someone help me to implment this in R ? the point is that, duplicate colnames, might not have duplicate entires.

Upvotes: 34

Views: 78018

Answers (5)

sneha patil
sneha patil

Reputation: 41

temp = matrix(seq_len(15), 5, 3)
colnames(temp) = c("A", "A", "B")

temp = as.data.frame.matrix(temp)
temp = temp[!duplicated(colnames(temp))]
temp = as.matrix(temp)

Upvotes: 3

Adam Erickson
Adam Erickson

Reputation: 6363

To remove a specific duplicate column by name, you can do the following:

test = cbind(iris, iris) # example with multiple duplicate columns
idx = which(duplicated(names(test)) & names(test) == "Species")
test = test[,-idx]

To remove all duplicated columns, it is a bit simpler:

test = cbind(iris, iris) # example with multiple duplicate columns
idx = which(duplicated(names(test)))
test = test[,-idx]

or:

test = cbind(iris, iris) # example with multiple duplicate columns
test = test[,!duplicated(names(test))]

Upvotes: 1

Holger Brandl
Holger Brandl

Reputation: 11192

Or assuming data.frames you could use subset:

subset(iris, select=which(!duplicated(names(.))))

Note that dplyr::select is not applicable here because it requires column-uniqueness in the input data already.

Upvotes: 19

saswat prusty
saswat prusty

Reputation: 19

Store all your duplicates into one vector say duplicates, and Use -duplicates with single bracket subsetting to remove duplicate columns.

       # Define vector of duplicate cols (don't change)
       duplicates <- c(4, 6, 11, 13, 15, 17, 18, 20, 22, 
            24, 25, 28, 32, 34, 36, 38, 40, 
            44, 46, 48, 51, 54, 65, 158)

      # Remove duplicates from food and assign it to food2
         food2 <- food[,-duplicates]

Upvotes: 0

David Arenburg
David Arenburg

Reputation: 92282

Let's say temp is your matrix

temp <- matrix(seq_len(15), 5, 3)
colnames(temp) <- c("A", "A", "B")

##      A  A  B
## [1,] 1  6 11
## [2,] 2  7 12
## [3,] 3  8 13
## [4,] 4  9 14
## [5,] 5 10 15

You could do

temp <- temp[, !duplicated(colnames(temp))]

##      A  B
## [1,] 1 11
## [2,] 2 12
## [3,] 3 13
## [4,] 4 14
## [5,] 5 15

Or, if you want to keep the last duplicated column, you can do

temp <- temp[, !duplicated(colnames(temp), fromLast = TRUE)] 

##       A  B
## [1,]  6 11
## [2,]  7 12
## [3,]  8 13
## [4,]  9 14
## [5,] 10 15

Upvotes: 60

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