ggplot not adding legend. What am I missing? very new to R

问题

I'm plotting three samples with ggplot but it's not adding a legend for the samples. It's not spitting out any error message so I'm not sure where I'm going wrong. I'd really appreicate some guidance.

I've tried to declare color for each sample for the legend manually but there is still no legend on the plot.

df<-data.frame(samples$V1, samples$V2, samples$V3, samples$V4, samples$V5, samples$V6, samples$V7)


CG_methplot <- ggplot(df, aes(x=samples$V1,))+
  scale_x_continuous(breaks=number_ticks(10))+
  xlab("bins")+
  ylab("mean CG methylation")+
  geom_point(aes(y=samples$V2), size=3, colour='#009933')+
  geom_point(aes(y=samples$V3), size=3, colour='#FF0000')+
  geom_point(aes(y=samples$V4), size=3, colour='#0033FF')+
  scale_color_manual(values=c("samples1"="009933", "sample2"="FF0000", "sample3" ="0033FF"))
CG_methplot

As requested, sample data.

head(df)

samples.V1 samples.V2 samples.V3 samples.V4 samples.V5 samples.V6 samples.V7
1          1   0.033636   0.027857   0.028830   0.029836   0.024457   0.024930
2          2   0.032094   0.029620   0.028005   0.028294   0.026220   0.024105
3          3   0.032011   0.027212   0.029728   0.028211   0.023812   0.025828
4          4   0.030857   0.029833   0.028907   0.027057   0.026433   0.025007
5          5   0.028480   0.028080   0.028553   0.024680   0.024680   0.024653
6          6   0.029445   0.027099   0.029346   0.025645   0.023699   0.025446

回答1:

library(reshape2)
melted <- melt(df, id.vars = "V1")

p <- ggplot(melted, aes(x = V1, y = value, colour = variable))
p + geom_point()

来源：https://stackoverflow.com/questions/21616688/ggplot-not-adding-legend-what-am-i-missing-very-new-to-r

标签

ggplot2

format

scale

legend