Legend with rainbow colours R

Question

I have been trying to create a legend for an R plot with the rainbow option but I am facing some difficulties.

I plot

plot(test$a,test$b, col = rainbow(length(test$s))[rank(test$s)])

with the colour assigned according to test$s. The problem is that test$s is equal for many values of the data frame test so if than I write

    legend('topright',legend=test.sub$s,col=rainbow(length(test.sub$s))
[rank(test.sub$s)])

I get in the legend all duplicates of test$s but the colours are correct. Since I don't want the duplicates I wrote

    legend('topright',legend=unique(test.sub$s),col=rainbow(length(test.sub$s))
[rank(test.sub$s])

but then all the colours are messed up!

Thanks in advance

Answer 1

您的问题是， unique(test.sub$s)的长度与rainbow(length(test.sub$s))[rank(test.sub$s] 。我的解决方案是：

col=rainbow(length(test.sub$s))[rank(test.sub$s)[!duplicated(test.sub$s)]]