R help - Sep 2008 - Summing up columns with NA elements in a data frame

Hi all,
When I try to sum a few columns in a data frame (which has NA?s randomly
distributed as elements), I am not able to get the summing operation to ignore
the NA?s.
Let me explain with the following code :
################################?
a<-structure(list(a1 = c(NA, 2, 3, NA, 5, 6, NA, 8, 9, NA), a2 = c(NA,
+ 4, 5, 5, NA, 7, 8, 8, NA, 10), a3 = c(2, NA, 6, 8, NA, 12, 14,
+ NA, 18, 20)), .Names = c("a1", "a2", "a3"),
row.names = c(NA,
+ -10L), class = "data.frame")
print(a)
a$a4<-a$a1+a$a2+a$a3 #method 1
print(a)
b<-apply(a,1,sum) #method 2
print(b)
d<-apply(a,1,FUN=function(x) (sum(x),na.rm=T)) # not the right syntax,
apparently - method 3
print(d)
######################################?
I would like to know how to make the na.rm=T to work, or any other solution.?
I am also mystified by the following result :
?####################################
attach(a)
a$a4<-a1+a2+a3 # method 4
detach(a)
print(a)
#############################?
Now, the row numbers (why?)?seem to get added - sometimes.
There are some things that I am missing here. Will appreciate all help in
understanding the issues here.
Thanking You,
Ravi

Try this:

a$a4 <- rowSums(a, na.rm = T)

On Tue, Sep 23, 2008 at 12:20 PM, ravi <rv15i at yahoo.se>
wrote:
> Hi all,
> When I try to sum a few columns in a data frame (which has NA's
randomly distributed as elements), I am not able to get the summing operation to
ignore the NA's.
> Let me explain with the following code :
> ################################
> a<-structure(list(a1 = c(NA, 2, 3, NA, 5, 6, NA, 8, 9, NA), a2 = c(NA,
> + 4, 5, 5, NA, 7, 8, 8, NA, 10), a3 = c(2, NA, 6, 8, NA, 12, 14,
> + NA, 18, 20)), .Names = c("a1", "a2", "a3"),
row.names = c(NA,
> + -10L), class = "data.frame")
> print(a)
> a$a4<-a$a1+a$a2+a$a3 #method 1
> print(a)
> b<-apply(a,1,sum) #method 2
> print(b)
> d<-apply(a,1,FUN=function(x) (sum(x),na.rm=T)) # not the right syntax,
apparently - method 3
> print(d)
> ######################################
> I would like to know how to make the na.rm=T to work, or any other
solution.
> I am also mystified by the following result :
>  ####################################
> attach(a)
> a$a4<-a1+a2+a3 # method 4
> detach(a)
> print(a)
> #############################
> Now, the row numbers (why?) seem to get added - sometimes.
> There are some things that I am missing here. Will appreciate all help in
understanding the issues here.
> Thanking You,
> Ravi
>
> ______________________________________________
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> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>


-- 
Henrique Dallazuanna
Curitiba-Paran?-Brasil
25? 25' 40" S 49? 16' 22" O