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How to remove a column from a data frame that contains same value in R?
If we have only one value in all of the rows of an R data frame then we might want to remove the whole column because the effect of that column will not make any sense in the data analysis objectives. Thus, instead of removing the column we can extract the columns that contains different values.
Example
set.seed(1001) x1<-sample(0:1,20,replace=TRUE) x2<-rep(5,20) x3<-sample(0:5,20,replace=TRUE) x4<-sample(1:10,20,replace=TRUE) df1<-data.frame(x1,x2,x3,x4) df1
Output
x1 x2 x3 x4 1 0 5 1 6 2 0 5 1 4 3 0 5 3 7 4 0 5 2 5 5 1 5 3 5 6 0 5 0 5 7 1 5 1 7 8 0 5 5 5 9 1 5 5 4 10 1 5 2 1 11 1 5 4 6 12 1 5 5 8 13 1 5 0 4 14 1 5 1 9 15 1 5 2 9 16 0 5 5 8 17 0 5 1 6 18 0 5 1 4 19 1 5 3 7 20 0 5 4 2
Removing column that contains 5 −
Example
df1[,c(1,3,4)]
Output
x1 x3 x4 1 0 1 6 2 0 1 4 3 0 3 7 4 0 2 5 5 1 3 5 6 0 0 5 7 1 1 7 8 0 5 5 9 1 5 4 10 1 2 1 11 1 4 6 12 1 5 8 13 1 0 4 14 1 1 9 15 1 2 9 16 0 5 8 17 0 1 6 18 0 1 4 19 1 3 7 20 0 4 2
Let’s have a look at another example −
Example
y1<-sample(1:3,20,replace=TRUE) y2<-sample(1:5,20,replace=TRUE) y3<-rep(1,20) y4<-sample(1:2,20,replace=TRUE) y5<-sample(1:6,20,replace=TRUE) y6<-sample(1:8,20,replace=TRUE) df2<-data.frame(y1,y2,y3,y4,y5,y6) df2
Output
y1 y2 y3 y4 y5 y6 1 3 2 1 1 3 1 2 2 2 1 2 3 5 3 2 5 1 1 2 6 4 2 4 1 1 4 6 5 1 1 1 1 1 4 6 1 2 1 1 3 6 7 1 3 1 2 5 2 8 3 2 1 2 5 1 9 1 3 1 1 3 6 10 3 1 1 2 6 1 11 3 3 1 2 4 2 12 2 4 1 2 5 5 13 3 5 1 2 4 7 14 3 2 1 1 1 5 15 3 1 1 2 3 1 16 2 4 1 2 5 5 17 2 3 1 2 3 6 18 3 4 1 1 1 6 19 1 1 1 1 6 5 20 1 3 1 1 6 1
Removing column 3 from data frame df2 −
Example
df2[,c(1,2,4,5,6)]
Output
y1 y2 y4 y5 y6 1 3 2 1 3 1 2 2 2 2 3 5 3 2 5 1 2 6 4 2 4 1 4 6 5 1 1 1 1 4 6 1 2 1 3 6 7 1 3 2 5 2 8 3 2 2 5 1 9 1 3 1 3 6 10 3 1 2 6 1 11 3 3 2 4 2 12 2 4 2 5 5 13 3 5 2 4 7 14 3 2 1 1 5 15 3 1 2 3 1 16 2 4 2 5 5 17 2 3 2 3 6 18 3 4 1 1 6 19 1 1 1 6 5 20 1 3 1 6 1
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