[R] sum(..., na.rm=TRUE) oddity

[rohan sadler]

Hi all,

I get two different results when using sum() and the switch na.rm. The 
result is correct when na.rm=FALSE.
Linux Redhat 7.3, R version 1.6.1.

I've had no luck searching the mail archives, so I was hoping somebody 
could explain/check this one for me. I will need to apply the function 
to missing data, simple as it is.

Code:

 x<-matrix(runif(20,0,5)%/%1,4,5)      # random matrix data set 4x5, 
values are integers between 0 and 4

coords<-c(2,3,3,4)     # choose any sub-matrix, with 
c(ymin,ymax,xmin,xmax) being row and column indices.

 occupied.counter<-function(coords){sum(x[coords[3]:coords[4],coords[1]:coords[2]])}

 occupied.counter(coords)
[1] 7

 occupied.counter<-function(coords){sum(x[coords[3]:coords[4],coords[1]:coords[2]], 
na.rm=TRUE)}

 occupied.counter(coords)
[1] 8


Cheers in advance

Rohan Sadler

-- 
Ecosystems Research Group (ERGO)
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