On Aug 10, 2011, at 11:04 AM, Anthony Ching Ho Ng wrote:
Dear R-help,
I wonder if you could give me some suggestions in how to do a union
join of two data frames as follow:
-> union join the common column, and insert a 0 if one is missing.
I made a function to perform the following, and I know it may not that
quite welly written, but it works.
Any suggestions are welcome, many thanks.
Anthony
q1 = data.frame(a=1,b=2,c=3,row.names="q1")
a b c
q1 1 2 3
q2 = data.frame(d=4,b=1,a=4, row.names="q2")
d b a
q2 4 1 4
-> myJoinColumns(q1,q2)
a b c d
q1 1 2 3 0
q2 4 1 0 4
> temp <- merge(q1,q2, all=TRUE)
> temp[is.na(temp)] <- 0
> temp
a b c d
1 1 2 3 0
2 4 1 0 4
myJoinColumns <- function(q1,q2){
allNames = sort(union(colnames(q1),colnames(q2)))
for (i in 1:length(allNames)){
t1 = which(colnames(q1) == allNames[i])
t2 = which(colnames(q2) == allNames[i])
if (length(t1) == 1){
sec1 = q1[,t1]
} else {
sec1 = 0
}
if (length(t2) == 1){
sec2 = q2[,t2]
} else {
sec2 = 0
}
if (i == 1){
qTable = matrix(c(sec1,sec2))
}else{
qTable = cbind(qTable,c(sec1,sec2))
}
}
colnames(qTable) = allNames
rownames(qTable) = c("q1","q2")
qTable
}
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______________________________________________
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PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
