On Wed, Mar 16, 2011 at 6:58 PM, jctoll <jct...@gmail.com> wrote: > Hi, > > I'm struggling to figure out the way to change the name of a column > from within a loop. The problem is I can't refer to the object by its > actual variable name, since that will change each time through the > loop. My xts object is A. > >> head(A) > A.Open A.High A.Low A.Close A.Volume A.Adjusted A.Adjusted.1 > 2007-01-03 34.99 35.48 34.05 34.30 2574600 34.30 11867800000 > 2007-01-04 34.30 34.60 33.46 34.41 2073700 34.41 11905860000 > 2007-01-05 34.30 34.40 34.00 34.09 2676600 34.09 11795140000 > 2007-01-08 33.98 34.08 33.68 33.97 1557200 33.97 11753620000 > 2007-01-09 34.08 34.32 33.63 34.01 1386200 34.01 11767460000 > 2007-01-10 34.04 34.04 33.37 33.70 2157400 33.70 11660200000 > > It's column names are: >> colnames(A) > [1] "A.Open" "A.High" "A.Low" "A.Close" > "A.Volume" "A.Adjusted" "A.Adjusted.1" > > I want to change the 7th column name: >> colnames(A)[7] > [1] "A.Adjusted.1" > > I need to do that through a reference to i: >> i > [1] "A" > > This works: >> colnames(get(i))[7] > [1] "A.Adjusted.1" > > And this is what I want to change the column name to: >> paste(i, ".MarketCap", sep = "") > [1] "A.MarketCap" > > But how do I make the assignment? This clearly doesn't work: > >> colnames(get(i))[7] <- paste(i, ".MarketCap", sep = "") > Error in colnames(get(i))[7] <- paste(i, ".MarketCap", sep = "") : > could not find function "get<-" > > Nor does this (it creates a new object "A.Adjusted.1" with a value of > "A.MarketCap") : > > assign(colnames(get(i))[7], paste(i, ".MarketCap", sep = "")) > > How can I change the name of that column within my big loop? Any > ideas? Thanks! > I usually make a copy of the object, change it, then overwrite the original:
tmp <- get(i) colnames(tmp)[7] <- "foo" assign(i,tmp) Hope that helps. > Best regards, > > > James > > ______________________________________________ > 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. > -- Joshua Ulrich | FOSS Trading: www.fosstrading.com ______________________________________________ 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.
