Sam, Your loop produces two jpegs but the second overwrites the first. What do you expect
levels(df[i,"f"]) to produce? (Think about it.) Try jpeg(filename=paste(i,".jpg",sep="")) and you may want to fix the titles as well. Peter Sam Player wrote:
# I have a dataframe with data and factors similar to the following: a <- rep(c("a", "b"), c(6,6)) df <- data.frame(f=a, d=rnorm(12)) df# I am trying to write a 'for' loop which will produce a jpeg histogram for each factor. I can individually isolate the data from a factor and produce a jpeg histogram like so:fnc <- function(x){ x <- df[df$f=="a", "d"] } y <- fnc(df[df$f=="a", "d"]) jpeg(filename="foo.jpeg") hist(y) dev.off()# I'm having trouble creating a loop repeating the process for all the other factors. The following is the best I could come up with. It produces a single jpeg histogram of the first factor titled with a list of all the factors.a <- rep(c("a", "b"), c(6,6)) df <- data.frame(f=a, d=rnorm(12)) df for (i in levels(df[,"f"])){ y <- df[df$f==i, 2] jpeg(filename=(levels(df[i,"f"]))) hist(y, main=levels(df[i,"f"])) dev.off() }# I'm obviously not understanding how loops work with factors. Can anybody point me in the right direction?
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