"Nelson Castillo" <[EMAIL PROTECTED]> wrote in news:[EMAIL PROTECTED]:
> Hi :-) > > I'm new to R and I started using it for a project (I'm the CS guy in > a group of statisticians helping them find out how to solve issues > as they come out). This is my first post to the list and I am > starting to learn R. > > Well, they were used to doing MCA analysis in other programs where > the data seems to be preprocessed automatically before running MCA. > > So, they need to process a data set that comes with N=1000000 of > elements, but there are really about N/100 distinct elements over > all the variables, so the MCA can be run in reasonable time > summarizing data. > > So, the question is: > > How can I turn x from: > > x <- > structure(list(weight = c(1, 1, 2, 1, 2), var1 = structure(c(1L, > 1L, 1L, 1L, 2L), .Label = c("A", "C"), class = "factor"), var2 = > structure(c(1L, > 1L, 1L, 1L, 2L), .Label = c("B", "D"), class = "factor")), .Names = > c("weight", "var1", "var2"), row.names = c(NA, 5L), class = > "data.frame") > > to: > > y <- > structure(list(weihgt = c(5L, 2L), var1 = structure(1:2, .Label = > c("A", "C"), class = "factor"), var2 = structure(1:2, .Label = > c("B", "D"), class = "factor")), .Names = c("weihgt", "var1", "var2" > ), class = "data.frame", row.names = c(NA, -2L)) > > using R? > > That is, from: > >> x > weight var1 var2 > 1 1 A B > 2 1 A B > 3 2 A B > 4 1 A B > 5 2 C D > > to: > >> y > weihgt var1 var2 > 1 5 A B > 2 2 C D > Does this suffice? s.wt <- with(x, aggregate(weight, by=list(var1=var1,var2=var2), sum) ) #> s.wt # var1 var2 x #1 A B 5 #2 C D 2 #then fix names names(s.wt)[3] <- "weight" #> s.wt # var1 var2 weight #1 A B 5 #2 C D 2 I believe that the reshape or reShape packages could do this in one step. -- David Winsemius > > The idea is that there is one occurrence of "A B" repeated 4 times > in the original table, > and it is summarized in the second table, computing the sum of the > weights. > > I solved the problem using Perl, but I'd like to know what I have to > read in order to > do it in R. > > Regards, > Nelson.- > ______________________________________________ R-help@r-project.org mailing list 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.