Add variables whilst ignoring NA`s using transform function

Question

I have a data frame with a large number of variables. I am creating new variables by adding together some of the old ones. The code I am using to do so is:

n         


        

Answer 1

Using rowSums and prod could help you out.

set.seed(007) # Generating some data
DF <- data.frame(V1=sample(c(50,NA,36,24,80, NA), 15, replace=TRUE),
                 V2=sample(c(70,40,NA,25,100, NA), 15, replace=TRUE),
                 V3=sample(c(20,26,34,15,78,40), 15, replace=TRUE))

transform(DF, Sum=rowSums(DF, na.rm=TRUE)) # Sum (a vector of values)
transform(DF, Prod=apply(DF, 1, FUN=prod, na.rm=TRUE)) # Prod (a vector of values)

# Defining a function for substracting (resta, in spanish :D)
resta <- function(x) Reduce(function(a,b) a-b,  x <- x[!is.na(x)])
transform(DF, Substracting=apply(DF, 1, resta))

# Defining a function for dividing 
div <- function(x) Reduce(function(a,b) a/b,  x <- x[!is.na(x)])
transform(DF, Divsion=apply(DF, 1, div))