On Sep 6, 2010, at 9:56 AM, Sergey Goriatchev wrote:
Hello everyone.
Say we have the following:
a <- matrix(c(-75, 3, 5, 9, 2, 3, 5), nrow=1, dim=list("06092010",
c("ES", "PT", "Z ", "CF", "GX", "ST", "EO")))
b <- matrix(c(-5, 2, 4, 12, 5), nrow=1, dim=list("06092010", c("PT",
"CF", "AT", "EM", "ST")))
d <- cbind(a, b)
I want to calculate sums of the columns that have similar column names
and then output this summary
What I want to have is an array that looks like:
ES PT Z CF...
-75 -2 5 11...
I tried the following, but it did not work:
aggregate(d, list(colnames(d)), sum)
ES is not in the duplicated column names so perhaps your English
specification is not what you meant:
> d
ES PT Z CF GX ST EO PT CF AT EM ST
06092010 -75 3 5 9 2 3 5 -5 2 4 12 5
> dupled <- colnames(d)[duplicated(colnames(d))]
> sapply(dupled, function(x) sum( d[, x]))
PT CF ST
3 9 3
If you wanted simple a sum over unique column names then it would have
been somewhat simpler (no need to construct a duplicated set):
> sapply(unique(colnames(d)), function(x) sum( d[, x]))
ES PT Z CF GX ST EO AT EM
-75 3 5 9 2 3 5 4 12
How can I achieve my objective?
Thank you in advance.
Sergey
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