How to combine two rows in data.table object in R by addition?

R Programming Server Side Programming Programming

To combine two rows in data.table object in R by addition, we can follow the below steps −

First of all, create a data.table object.
Then, using plus sign (+) to add two rows and store the addition in one of the rows.
After that, remove the row that is not required by subsetting with single square brackets.

Example

Create the data.table object

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

library(data.table)
x<-sample(1:5,25,replace=TRUE)
y<-sample(1:5,25,replace=TRUE)
z<-sample(1:5,25,replace=TRUE)
DT<-data.table(x,y,z)
DT

Output

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

Add two rows

Using plus sign to add row 1 and row 2 then storing the sum in row 1 −

library(data.table)
x<-sample(1:5,25,replace=TRUE)
y<-sample(1:5,25,replace=TRUE)
z<-sample(1:5,25,replace=TRUE)
DT<-data.table(x,y,z)
DT[1,]<-DT[1,]+DT[2,]
DT

Output

Remove the row which is not required

Using single square subsetting to remove 2^nd row from data.table object DT −

library(data.table)
x<-sample(1:5,25,replace=TRUE)
y<-sample(1:5,25,replace=TRUE)
z<-sample(1:5,25,replace=TRUE)
DT<-data.table(x,y,z)
DT[1,]<-DT[1,]+DT[2,]
DT[-2,]

Output

Nizamuddin Siddiqui

Updated on: 09-Nov-2021

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