R: changing plot colors

I made the following plot in R :

library(MASS)    a = rnorm(100, 10, 10)    b = rnorm(100, 10, 5)    c = rnorm(100, 5, 10)    group <- sample( LETTERS[1:4], 100, replace=TRUE, prob=c(0.25, 0.25, 0.25, 0.25) )    d = data.frame(a, b, c, group)  d$group = as.factor(d$group)      parcoord(d[, c(3, 1, 2)], col = 1 + (0:149) %/% 50)  title(main = "Plot", xlab = "Variable", ylab = "Values")  axis(side = 2, at = seq(0, 5, 0.1),       tick = TRUE, las = 1)  

Can someone please show me how to color each line in this plot according the value of "d$group" and add a legend in the corner of the screen?

I think the following line of code changes the color of lines per value of "d$group":

parcoord(d[, c(3, 1, 2)], col = d$group)  

And this line of code creates a legend:

legend( "topleft", c("A", "B", "C", "D"),   text.col=c("blue", "red", "yellow", "green") )    title("Legend",        cex.main = 1.1)  

But I am not sure how to have the colors from the legend match the real colors. I tried:

legend( "topleft", c("A", "B", "C", "D"),   text.col= d$group)  

But this did not work. Can someone please show me how to fix this?

Thanks

EDIT: is there a way to run the code (provided in the answer) if variable "C" is a factor?

e.g.

a = rnorm(100, 10, 10)    b = rnorm(100, 10, 5)    c <- sample( LETTERS[1:2], 100, replace=TRUE, prob=c(0.5,0.5) )    group <- sample( LETTERS[1:4], 100, replace=TRUE, prob=c(0.25, 0.25, 0.25, 0.25) )    d = data.frame(a, b, c, group)  d$group = as.factor(d$group)  d$c = as.factor(d$c)      library(tidyverse)  library(ggplot2)  library(dplyr)    d %>%     mutate(rn = row_number()) %>%     pivot_longer(a:c) %>%     ggplot(aes(name, value, group = rn, color = group)) +    scale_x_discrete(expand = expansion(0, 0)) +    geom_line()  

https://stackoverflow.com/questions/65839197/r-changing-plot-colors January 22, 2021 at 12:11PM