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How to add two columns if both contains missing values in R?
If we want to add two columns of an R data frame and each of them contains missing values then the addition of columns can be done in one of the following ways −
Adding both the column values if they are numeric.
Returning numeric if one of the columns has missing value.
Returning NA if both the columns have missing value.
To this we can take help of apply function and ifelse function as shown in the below given examples.
Example 1
Following snippet creates a sample data frame −
x1<-sample(c(NA,1,2),20,replace=TRUE) x2<-sample(c(NA,5),20,replace=TRUE) df1<-data.frame(x1,x2) df1
The following dataframe is created −
x1 x2 1 1 NA 2 1 5 3 2 5 4 1 5 5 2 5 6 NA NA 7 2 NA 8 1 NA 9 1 5 10 NA NA 11 1 NA 12 2 NA 13 NA NA 14 NA NA 15 1 NA 16 1 5 17 NA NA 18 1 NA 19 2 NA 20 NA 5
To add columns of df1, add the following code to the above snippet −
x1<-sample(c(NA,1,2),20,replace=TRUE) x2<-sample(c(NA,5),20,replace=TRUE) df1<-data.frame(x1,x2) df1$Sum<-apply(cbind(df1$x1,df1$x2),1,function(x) ifelse(all(is.na(x)),NA,sum(x,na.rm=T))) df1
Output
If you execute all the above given snippets as a single program, it generates the following output: −
x1 x2 Sum 1 1 NA 1 2 1 5 6 3 2 5 7 4 1 5 6 5 2 5 7 6 NA NA NA 7 2 NA 2 8 1 NA 1 9 1 5 6 10 NA NA NA 11 1 NA 1 12 2 NA 2 13 NA NA NA 14 NA NA NA 15 1 NA 1 16 1 5 6 17 NA NA NA 18 1 NA 1 19 2 NA 2 20 NA 5 5
Example 2
Following snippet creates a sample data frame −
y1<-sample(c(NA,rnorm(2)),20,replace=TRUE) y2<-sample(c(NA,rnorm(2)),20,replace=TRUE) df2<-data.frame(y1,y2) df2
The following dataframe is created −
y1 y2 1 0.5109281 -0.6697566 2 NA -0.1898259 3 NA -0.1898259 4 -0.9540862 -0.6697566 5 NA -0.1898259 6 NA -0.1898259 7 NA NA 8 0.5109281 -0.6697566 9 NA NA 10 0.5109281 NA 11 0.5109281 -0.6697566 12 -0.9540862 NA 13 -0.9540862 -0.6697566 14 NA -0.1898259 15 0.5109281 -0.1898259 16 NA -0.1898259 17 0.5109281 NA 18 NA -0.6697566 19 NA -0.1898259 20 NA NA
To add columns of df2, add the following code to the above snippet −
y1<-sample(c(NA,rnorm(2)),20,replace=TRUE) y2<-sample(c(NA,rnorm(2)),20,replace=TRUE) df2<-data.frame(y1,y2) df2$Sum<-apply(cbind(df2$y1,df2$y2),1,function(x) ifelse(all(is.na(x)),NA,sum(x,na.rm=T))) df2
Output
If you execute all the above given snippets as a single program, it generates the following output: −
y1 y2 Sum 1 0.5109281 -0.6697566 -0.1588286 2 NA -0.1898259 -0.1898259 3 NA -0.1898259 -0.1898259 4 -0.9540862 -0.6697566 -1.6238429 5 NA -0.1898259 -0.1898259 6 NA -0.1898259 -0.1898259 7 NA NA NA 8 0.5109281 -0.6697566 -0.1588286 9 NA NA NA 10 0.5109281 NA 0.5109281 11 0.5109281 -0.6697566 -0.1588286 12 -0.9540862 NA -0.9540862 13 -0.9540862 -0.6697566 -1.6238429 14 NA -0.1898259 -0.1898259 15 0.5109281 -0.1898259 0.3211022 16 NA -0.1898259 -0.1898259 17 0.5109281 NA 0.5109281 18 NA -0.6697566 -0.6697566 19 NA -0.1898259 -0.1898259 20 NA NA NA
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