[R] by() subset by factor gives unexpected results

I am having trouble understanding how the 'by' function works. Using this bit of code: i <- data.frame(x=c(1,2,3), y=c(0,0,0), B=c("red","blue","blue")) j <- data.frame(x=c(1,2,3), y=c(1,1,1), B=c('red','blue','green')) plot(0, 0, type="n", xlim=c(0,4), ylim=c(0,1)) by(i, i$B, function(s){

Re: [R] by() subset by factor gives unexpected results

The answer was (thanks to Mark Leeds) to do with the use of a factor instead of a vector. on [2017-08-05] at 08:57 Myles English writes: > I am having trouble understanding how the 'by' function works. Using > this bit of code: > > i <- data.frame(x=c(1,2,3), y=c(0,0,0), B=c(&qu