Plot multiple lines in one graph

Question

Trying to use ggplot to plot multiple lines into one graph, but not sure how to do so with my dataset. Not sure whether I need to change the datastructure or not (transpose?)

Data looks like this:

Company   2011   2013
Company1  300    350
Company2  320    430
Company3  310    420

I also tried it transposed:

Year   Company1  Company2  Company3
2011   300       320       310 
2013   350       430       420

And for this I can plot 1 of the values using;

ggplot(data=df, aes(x=Year, y=Company1)) + geom_line(colour="red") + geom_point(colour="red", size=4, shape=21, fill="white")

But I don't know how to combine all the companies as I don't have an object 'Company' anymore to group on. Any suggestions?

Answer 1

You should bring your data into long (i.e. molten) format to use it with ggplot2:

library("reshape2")
mdf <- melt(mdf, id.vars="Company", value.name="value", variable.name="Year")

And then you have to use aes( ... , group = Company ) to group them:

ggplot(data=mdf, aes(x=Year, y=value, group = Company, colour = Company)) +
    geom_line() +
    geom_point( size=4, shape=21, fill="white")

Answer 2

Instead of using the outrageously convoluted data structures required by ggplot2, you can use the native R functions:

tab<-read.delim(text="
Company 2011 2013
Company1 300 350
Company2 320 430
Company3 310 420
",as.is=TRUE,sep=" ",row.names=1)

tab<-t(tab)

plot(tab[,1],type="b",ylim=c(min(tab),max(tab)),col="red",lty=1,ylab="Value",lwd=2,xlab="Year",xaxt="n")
lines(tab[,2],type="b",col="black",lty=2,lwd=2)
lines(tab[,3],type="b",col="blue",lty=3,lwd=2)
grid()
legend("topleft",legend=colnames(tab),lty=c(1,2,3),col=c("red","black","blue"),bg="white",lwd=2)
axis(1,at=c(1:nrow(tab)),labels=rownames(tab))

Answer 3

The answer by @Federico Giorgi was a very good answer. It helpt me. Therefore, I did the following, in order to produce multiple lines in the same plot from the data of a single dataset, I used a for loop. Legend can be added as well.

plot(tab[,1],type="b",col="red",lty=1,lwd=2, ylim=c( min( tab, na.rm=T ),max( tab, na.rm=T ) )  )
for( i in 1:length( tab )) { [enter image description here][1]
lines(tab[,i],type="b",col=i,lty=1,lwd=2)
  } 
axis(1,at=c(1:nrow(tab)),labels=rownames(tab))