error while plotting multiple lines using ggplot

Question

I would like to plot four lines and the data is randomly generated below:

trE <- runif(12, 0.5, 0.8)
teE <- runif(12, 0.8, 1)
trES <- runif(12, 0, 0.3)
teES <- runif(12, 0.3, 0.5)
plotData <- data.frame(k=1:12, trE=trE, teE=teE, trES=trES, teES=teES)

I have plotted it using the below code:

ggplot(plotData, aes(k)) + 
  geom_line(aes(y = trE, colour = "Tr E")) + 
  geom_line(aes(y = teE, colour = "Te E")) +
  geom_line(aes(y = trES, colour = "Tr ES"), linetype="dashed") + 
  geom_line(aes(y = teES, colour = "Te ES"), linetype="dashed") +
  geom_hline(aes(yintercept = 0.5), linetype="dotted",colour='red') +
  scale_colour_manual(values=c("black", "orange","black", "orange"), 
                      labels=c("Tr E", "Te E", "Tr ES", "Te ES")) +
  scale_x_discrete(limits=1:12) +
  theme_bw()

But the output is not as expected:

The line colors are messed up and they should be in the order: "orange","black", "orange", "black" in the plot.

ggplot(plotData, aes(k)) + 
  geom_line(aes(y = trE, colour = "black")) + 
  geom_line(aes(y = teE, colour = "orange")) +
  geom_line(aes(y = trES, colour = "black"), linetype="dashed") + 
  geom_line(aes(y = teES, colour = "orange"), linetype="dashed") +
  geom_hline(aes(yintercept = 0.5), linetype="dotted",colour='red') +
  scale_colour_manual(values=c("black", "orange","black", "orange"), 
                      labels=c("Tr E", "Te E", "Tr ES", "Te ES")) +
  scale_x_discrete(limits=1:12) +
  theme_bw()

However, in this plot, the line colors are as expected but the labels are not as expected.

Do you have any thoughts for this weird behavior? or point me to the missing details.

update:

plotDataLong <- plotData %>% tidyr::gather(Error, value, 2:5)

ggplot(plotDataLong, aes(k, value, col=Error)) + geom_line() + 
  geom_hline(aes(yintercept = 0.5), linetype="dotted",colour='red') +
  scale_colour_manual(values=c("black", "orange","black", "orange"), 
                      labels=c("Tr E", "Te E", "Tr ES", "Te ES")) +
  scale_linetype(labels=c("solid","solid","dashed","dashed"))

Though the code is greatly simplified, the linetypes are not as expected.

Much better to tidy your data (tidyr::gather) before using ggplot. Greatly simplifies the code — Richard Telford
– Richard Telford, Commented Oct 3, 2017 at 13:47

Marco Sandri · Accepted Answer · 2017-10-04 13:47:56Z

1

set.seed(1)
trE <- runif(12, 0.5, 0.8)
teE <- runif(12, 0.8, 1)
trES <- runif(12, 0, 0.3)
teES <- runif(12, 0.3, 0.5)
plotData <- data.frame(k=1:12, trE=trE, teE=teE, trES=trES, teES=teES)

library(ggplot2)
ggplot(plotData, aes(k)) + 
  geom_line(aes(y = trE, colour = "Tr E"),lwd=1) + 
  geom_line(aes(y = teE, colour = "Te E"),lwd=1) +
  geom_line(aes(y = trES, colour = "Tr ES"), linetype="dashed",lwd=1) + 
  geom_line(aes(y = teES, colour = "Te ES"), linetype="dashed",lwd=1) +
  geom_hline(aes(yintercept = 0.5), linetype="dotted",colour='red') +
  scale_colour_manual(
     values=c("Te E"="orange","Tr E"="black", "Te ES"="orange", "Tr ES"="black"),
     breaks=c("Te E", "Tr E", "Te ES", "Tr ES")) +
  scale_x_discrete(limits=1:12) +
  theme_bw() +
  guides(colour = guide_legend(keywidth = 2, 
    override.aes = list(linetype = c("solid", "solid", "dashed", "dashed"))))

edited Oct 4, 2017 at 13:47

answered Oct 3, 2017 at 15:15

Marco Sandri

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4 Comments

Prradep Over a year ago

Please check, the colors and line types are not as expected(or given in the commands).

Prradep Over a year ago

+1 for the mistake identified. Still, the labels are not in sync. There are no dashed labels for Te ES, Tr ES. How to make it show these expected changes?

Prradep Over a year ago

yes.. exactly. The dashed lines are not present in the labels(sorry, I meant legend).

Prradep Over a year ago

Thanks for the expected output. Alternatively, it can be achieved easily using tidyr::gather.

Prradep · Accepted Answer · 2017-10-05 07:33:44Z

As per @Richard's suggestion, I have tried using tidyr::gather and the expected solutions below.

plotDataLong <- plotData %>% tidyr::gather(Error, value, 2:5)

ggplot(plotDataLong, aes(k, value, col=Error,linetype=Error)) + geom_line() +
  geom_hline(aes(yintercept = 0.5), linetype="dotted",colour='red') +
  scale_colour_manual(values=c("black", "black", "orange", "orange"),
                      name="Errors",
                      breaks=c('teE', 'teES',  'trE', 'trES'),
                      labels=c("Te E", "Te ES", "Tr E", "Tr ES")) +
  scale_linetype_manual(labels=c("Te E", "Te ES", "Tr E", "Tr ES"),
                 name="Errors",
                 breaks=c('teE', 'teES',  'trE', 'trES'),
                 values=c("solid","dashed","solid","dashed"))

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