How to remove repeated column names in a data.table object in R?

In data analysis, we sometimes deal with duplicated data or just the representation of the data with same name. One such situation is column names are same for two columns in a data.table object. For this purpose, we can make use of which function with the combination of duplicated function and set the output of that duplicate to NULL to remove the repeated column names.

Example1

Loading data.table package and creating a data.table object −

library(data.table)
x1<−rnorm(20)
DT1<−data.table(x1,x1)
DT1

Output

      x1          x1
1: −1.65034927 −1.65034927
2: −1.95441645 −1.95441645
3: 2.03530252 2.03530252
4: −2.07789754 −2.07789754
5: −1.31558491 −1.31558491
6: 0.69256432 0.69256432
7: 1.83924420 1.83924420
8: −1.59751233 −1.59751233
9: −0.12015454 −0.12015454
10: 0.46507856 0.46507856
11: 1.00867249 1.00867249
12: 1.76181383 1.76181383
13: 0.35151845 0.35151845
14: −0.29470885 −0.29470885
15: −0.01617467 −0.01617467
16: 1.28775955 1.28775955
17: −1.80266832 −1.80266832
18: −0.70682196 −0.70682196
19: −2.07815278 −2.07815278
20: 0.43574626 0.43574626

Removing one x1 from DT1 −

DT1[,which(duplicated(names(DT1))):=NULL]
DT1

Output

      x1
1: −1.65034927
2: −1.95441645
3: 2.03530252
4: −2.07789754
5: −1.31558491
6: 0.69256432
7: 1.83924420
8: −1.59751233
9: −0.12015454
10: 0.46507856
11: 1.00867249
12: 1.76181383
13: 0.35151845
14: −0.29470885
15: −0.01617467
16: 1.28775955
17: −1.80266832
18: −0.70682196
19: −2.07815278
20: 0.43574626

Example2

y1<−rpois(20,5)
DT2<−data.table(y1,y1)
DT2

Output

 y1 y1
1: 6 6
2: 5 5
3: 7 7
4: 5 5
5: 2 2
6: 3 3
7: 6 6
8: 5 5
9: 5 5
10: 3 3
11: 3 3
12: 4 4
13: 3 3
14: 6 6
15: 4 4
16: 5 5
17: 4 4
18: 3 3
19: 1 1
20: 2 2

Removing one y1 from DT2 −

DT2[,which(duplicated(names(DT2))):=NULL]
DT2

Output

  y1
1: 6
2: 5
3: 7
4: 5
5: 2
6: 3
7: 6
8: 5
9: 5
10: 3
11: 3
12: 4
13: 3
14: 6
15: 4
16: 5
17: 4
18: 3
19: 1
20: 2

Nizamuddin Siddiqui

Updated on 05-Feb-2021 08:00:04

• Related Questions & Answers
• How to remove repeated numbers in sequence in R data frame column?
• How to remove column names from an R data frame?
• How to remove continuously repeated duplicates in an R data frame column?
• How to remove a common suffix from column names in an R data frame?
• How to change the repeated row names and column names to a sequence in a matrix in R?
• How to remove underscore from column names of an R data frame?
• How to remove the row names or column names from a matrix in R?
• How to change the column names and row names of a data frame in R?
• How to create a data frame with a column having repeated values in R?
• How to convert a column values to column names in R?
• How to remove a character in an R data frame column?
• How to remove rows in an R data frame using row names?
• How to remove a column from an R data frame?
• How to remove names from a named vector in R?
• How to deal with missing column for row names when converting data frame to data.table object in R?