How to find the percentage of zeros in each column of a data.table object in R?

To find the percentage of zeros in each column of a data.table object in R, we can follow the below steps −

• First of all, create a data.table object.

• Then, use colSums function along with nrow function to find the percentage of zeros in each column.

Example 1

Create the data.table object

Let’s create a data.table object as shown below −

library(data.table) y1<-round(rnorm(25,1),0) y2<-round(rnorm(25,1),0) y3<-round(rnorm(25,1),0) y4<-round(rnorm(25,1),0) DT1<-data.table(y1,y2,y3,y4) DT1

Output

On executing, the above script generates the below output(this output will vary on your system due to randomization) −

  y1 y2 y3 y4 1:  1  2  1 2 2:  2 -1  1 1 3:  2  0  1 2 4:  2  2  0 3 5:  3  1  0 2 6:  1  1  2 1 7:  1  4  2 2 8:  1  2  1 0 9:  1 -1  1 0 10: 1  1  2 -1 11: 1  1  0 0 12: 2  1  0 2 13: 0  0  1 1 14: 0  0  1 2 15: 0  2  0 1 16: 0 -1  1 1 17: 1  1  1 0 18: 2  2  1 0 19: 0  1  2 0 20: 1  0  0 1 21: 0  0  0 3 22: 1  3  3 2 23: 2  1  1 1 24: 1  2  1 1 25: 1  1  1 0    y1 y2 y3 y4

Find the percentage of zeros

Using colSums function along with nrow function to find the percentage of zeros in each column of data.table object DT1 −

library(data.table) y1<-round(rnorm(25,1),0) y2<-round(rnorm(25,1),0) y3<-round(rnorm(25,1),0) y4<-round(rnorm(25,1),0) DT1<-data.table(y1,y2,y3,y4) (colSums(DT1==0)/nrow(DT1))*100

Output

y1 y2 y3 y4 24 20 28 28

Example 2

Create the data.table object

Let’s create a data.table object as shown below −

library(data.table) c1<-sample(0:5,25,replace=TRUE) c2<-sample(0:5,25,replace=TRUE) c3<-sample(0:5,25,replace=TRUE) c4<-sample(0:5,25,replace=TRUE) DT2<-data.table(c1,c2,c3,c4) DT2

Output

On executing, the above script generates the below output(this output will vary on your system due to randomization) −

 c1 c2 c3 c4 1: 1 5 0 5 2: 3 2 2 5 3: 3 3 2 4 4: 3 5 2 1 5: 2 4 1 4 6: 0 2 1 3 7: 3 1 3 2 8: 1 3 3 4 9: 2 3 0 2 10: 1 3 5 4 11: 1 2 0 4 12: 3 3 5 1 13: 1 5 5 5 14: 1 1 4 4 15: 2 4 1 4 16: 3 5 4 3 17: 3 1 5 4 18: 5 4 5 2 19: 5 0 0 1 20: 4 5 2 2 21: 3 0 5 0 22: 0 5 5 3 23: 2 5 1 0 24: 4 5 5 1 25: 3 4 5 2 c1 c2 c3 c4

Find the percentage of zeros

Using colSums function along with nrow function to find the percentage of zeros in each column of data.table object DT2 −

library(data.table) c1<-sample(0:5,25,replace=TRUE) c2<-sample(0:5,25,replace=TRUE) c3<-sample(0:5,25,replace=TRUE) c4<-sample(0:5,25,replace=TRUE) DT2<-data.table(c1,c2,c3,c4) (colSums(DT2==0)/nrow(DT2))*100

Output

c1 c2 c3 c4 8 8 16 8