Multiple data lines in a single ggplot2

Question

I would like to plot multiple lines in a single ggplot, where each line would represent relationship between x and y given two or more parameters.

I know how to do that for one parameter:

Take following example data:

library(ggplot2) library(reshape2) rs = data.frame(seq(200, 1000, by=200), runif(5), runif(5), rbinom(n = 5, size = 1, prob = 0.5)) names(rs) = c("x_", "var1", "var2", "par") melted = melt(rs, id.vars="x_") ggplot(data = melted, aes(x = x_, y = value, group = variable, col = variable)) + geom_point() + geom_line(linetype = "dashed")

This plots three lines one for var1, one for var2 and one for par.

However, I would like four lines: one for var1 given par=0 and another one for var1 given par=1, and the same then again for var2.

How would this scale up, for example if I want that the condition is a combination of multiple parameters (e.g. par2 + par)?

Marius · Accepted Answer · 2019-01-25 01:07:20Z

If you melt the data in a different way, you can use par to change the shape and linetype of your lines, so it's nice and clear which line is which:

rs_melt = melt(rs, id.vars = c("x_", "par")) ggplot(rs_melt, aes(x = x_, y = value, colour = variable, shape = factor(par), linetype = factor(par))) + geom_line(size = 1.1) + geom_point(size = 3) + labs(shape = "par", linetype = "par")

Output:

Nice answer. May I suggest adding something like + theme(legend.key.width = unit(3, "lines")) to the plot? That would make the two linetypes more distinct in the par legend. At the default size, the circle / triangle shapes cover up breaks in the dashed line.

George · Accepted Answer · 2019-01-25 01:02:10Z

You need to adjust your melt function and add a group column which has both par and var details. I think below is what you want?

library(reshape) library(ggplot2) rs = data.frame(seq(200, 1000, by=200), runif(5), runif(5), rbinom(n = 5, size = 1, prob = 0.5)) names(rs)=c("x_", "var1", "var2", "par") melted = melt(rs, id.vars=c("x_", "par")) melted$group <- paste(melted$par, melted$variable) ggplot(data=melted, aes(x=x_, y=value, group =group, col=group))+ geom_point() + geom_line(linetype = "dashed")

Is it possible to rename group legend, so that it won't just say "0 var1", "1 var1" etc. but "par: 0, var1"? How would you put some of this information directly on line?
To rename your groups in the legend you just have to rename the variables in the dataframe, something like melted$group <- factor(melted$group, levels =c("0 var1", "0 var2", "1 var1", "1 var2"), labels=c("a", "b", "c", "d")). What information are you wanting on the line? if you want the labels there are plenty of packages and solutions that might help (stackoverflow.com/questions/29357612/…)

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