[R] Adding across columns ignoring NA

[Berend Hasselman]

On 20-07-2013, at 06:37, Jin Choi <oohpsjin at gmail.com> wrote:

> I am having difficulty finding a solution to devising an R code to do the
> following:
> 
> I have 5 numerical variables and I would like to create a new variable that
> is the sum of those 5 variables. However, there are many NA values
> throughout these 5 variables and everytime I run the following code
> 
> new_variable=var1+var2+var3+var4+var5
> 
> I get NA as the sum whenever one of those 5 variables are NA. I cannot
> figure out a way to have new_variable represent the sum for only those
> values that are not NA.
> 
> As an example,
> if var1=3
> var2=3
> var3=NA
> var4=NA
> var5=2
> 
> I would like new_variable to be 8 but I keep getting NA and I have
> unsuccessfully tried different methods to do so. I feel there is a simple
> method to solve my problem but I am unaware of such. I would appreciate any
> guidance!

?sum

Have a look at the na.rm argument of sum.

Berend