I am fairly new to R and would like help with the problem below. I am
trying to sum and count several rows in the data frame yy below. All works
well as in example 1. When I try to add the columns, with an NA in Q21, I
get as NA as mySum. I would like NA to be treated as O, or igored.
I wrote a function to try to count an NA element as 0, Example 3 function.
It works with a few warnings, Example 4, but still gives NA instead of the
addition when there is an NA in an element.
In Example 6 & 7, I tried using sum() but it just sums the whole data
frame, I think,
How do I add together several columns giving the result for each row in
mySum? NA should be treated as a 0. Please, note, I do not want to sum all
the columns, as I think rowSums would do, just the selected ones.
Thanks for your help.
Ian,
> yy <- read.table( header = T, sep=",", text = ## to create a data frame
+ "Q20, Q21, Q22, Q23, Q24
+ 0,1, 2,3,4
+ 1,NA,2,3,4
+ 2,1, 2,3,4")
+ yy
Q20 Q21 Q22 Q23 Q24
1 0 1 2 3 4
2 1 NA 2 3 4
3 2 1 2 3 4
> x <- transform( yy, ############## Example 1
+ mySum = as.numeric(Q20) + as.numeric(Q22) + as.numeric(Q24),
+ myCount =
as.numeric(!is.na(Q20))+as.numeric(!is.na(Q21))+as.numeric(!is.na(Q24))
+ )
+ x
Q20 Q21 Q22 Q23 Q24 mySum myCount
1 0 1 2 3 4 6 3
2 1 NA 2 3 4 7 2
3 2 1 2 3 4 8 3
>
+ x <- transform( yy, ################ Example 2
+ mySum = as.numeric(Q20) + as.numeric(Q21) + as.numeric(Q24),
+ myCount =
as.numeric(!is.na(Q20))+as.numeric(!is.na(Q21))+as.numeric(!is.na(Q24))
+ )
+ x
Q20 Q21 Q22 Q23 Q24 mySum myCount
1 0 1 2 3 4 5 3
2 1 NA 2 3 4 NA 2
3 2 1 2 3 4 7 3
> NifAvail <- function(x) { if (is.na(x)) x<-0 else x <- x
############### Example 3
+ return(as.numeric(x))
+ } #end function
+ NifAvail(5)
[1] 5
+ NifAvail(NA)
[1] 0
> x <- transform( yy,
+ mySum = NifAvail(Q20) + NifAvail(Q22) + NifAvail(Q24),
############### Example 4
+ myCount =
as.numeric(!is.na(Q20))+as.numeric(!is.na(Q21))+as.numeric(!is.na(Q24))
+ )
Warning messages:
1: In if (is.na(x)) x <- 0 else x <- x :
the condition has length > 1 and only the first element will be used
2: In if (is.na(x)) x <- 0 else x <- x :
the condition has length > 1 and only the first element will be used
3: In if (is.na(x)) x <- 0 else x <- x :
the condition has length > 1 and only the first element will be used
> x
Q20 Q21 Q22 Q23 Q24 mySum myCount
1 0 1 2 3 4 6 3
2 1 NA 2 3 4 7 2
3 2 1 2 3 4 8 3
> x <- transform( yy,
+ mySum = NifAvail(Q20) + NifAvail(Q21) + NifAvail(Q24),
################ Example 5
+ myCount =
as.numeric(!is.na(Q20))+as.numeric(!is.na(Q21))+as.numeric(!is.na(Q24))
+ )
Warning messages:
1: In if (is.na(x)) x <- 0 else x <- x :
the condition has length > 1 and only the first element will be used
2: In if (is.na(x)) x <- 0 else x <- x :
the condition has length > 1 and only the first element will be used
3: In if (is.na(x)) x <- 0 else x <- x :
the condition has length > 1 and only the first element will be used
> x
Q20 Q21 Q22 Q23 Q24 mySum myCount
1 0 1 2 3 4 5 3
2 1 NA 2 3 4 NA 2
3 2 1 2 3 4 7 3
> x <- transform( yy, ############
Example 6
+ mySum = sum(as.numeric(Q20), as.numeric(Q21), as.numeric(Q23), na.rm=T),
+ myCount =
as.numeric(!is.na(Q20))+as.numeric(!is.na(Q21))+as.numeric(!is.na(Q24))
+ )
+ x
Q20 Q21 Q22 Q23 Q24 mySum myCount
1 0 1 2 3 4 14 3
2 1 NA 2 3 4 14 2
3 2 1 2 3 4 14 3
> x <- transform( yy, #############
Example 7
+ mySum = sum(as.numeric(Q20), as.numeric(Q22), as.numeric(Q23), na.rm=T),
+ myCount =
as.numeric(!is.na(Q20))+as.numeric(!is.na(Q21))+as.numeric(!is.na(Q24))
+ )
+ x
Q20 Q21 Q22 Q23 Q24 mySum myCount
1 0 1 2 3 4 18 3
2 1 NA 2 3 4 18 2
3 2 1 2 3 4 18 3
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