Scatterplot: color and italicize axis labels

Question

in a R scatterplot I want to give the Y-Axis labels colours and make part bold, other parts italic. I start from a very simple plotting script, where everything is done, except the making the font bold, italic and giving it a colour:

png("test.png", height=800, width=600, pointsize=15)
par(mar=c(5,12,.25,1))
textA=seq(0,100,25)
textB=c("start","intermediate1","intermediate2","intermediate3","stop")
plot(c(0,runif(8),1),c(0,runif(8),1),axes=F,ylab=NA)
axis(1)
axis(2, at=seq(0,1,.25), labels=paste(textA,"-",textB,sep=""),las=2,cex.axis=1.5)
dev.off()

Question: How can I make the textA bold and coloured (red) and at the same time make the textB just italic, not bold, standard colour (black).

Thanks so much.

Answer 1

I would use axis for both textA and textB, then play around with line until you have an acceptable spacing.

EDIT: I don't know how to have different colours and fonts within a label. As a workaround, you can put both texts closely together by using text with a variable x-position. If you resize the window, you might have to adjust the offsets.

par(mar=c(5,13,.25,1))
textA=seq(0,100,25)
textB=c("start","intermediate1","intermediate2","intermediate3","stop")
plot(c(0,runif(8),1),c(0,runif(8),1),axes=F,ylab=NA)
axis(1)

# add textA and textB
axis(2, at=seq(0,1,.25), labels=textB, font=3, col.axis=1,las=2,cex.axis=1.5, line=1)
text(x=c(-0.3,-0.55,-0.55,-0.55,-0.3), y=seq(0,1,.25), textA, xpd=NA, col=2, font=2, cex=1.5)

# check which offset we need for textA:
# abline(v=seq(-1,0,.1), xpd=NA, col=2)
# text(,x=seq(-1,0,.1),y=rep(0,11),labels=seq(-1,0,.1),xpd=NA)

Answer 2

I would do that with ggplot2 as follows:

# create a dataframe
x <- c(0,runif(8),1)
y <- c(0,runif(8),1)
df <- as.data.frame(cbind(x, y))

# loading ggplot2 package
require(ggplot2)

# creating the plot
ggplot(df, aes(x=x, y=y)) + 
  geom_point(shape = 21, size = 4) +
  scale_x_continuous("x-axis-label") +
  scale_y_continuous("", breaks=c(0,0.25,0.50,0.75,1.00),
                     labels=c("start","intermediate1","intermediate2","intermediate3","stop")) + 
  theme_classic() +
  theme(axis.text.x = element_text(size=14, face="italic"),
        axis.text.y = element_text(size=14, colour = "red", face="bold"),
        axis.title.x = element_text(vjust=-1))

The result: