Rscript plot for y-axis

[kushald]

Hi

I am plotting 2 y-axis graph. I have given the script

pdf("plot.pdf")
gene_lens<- read.table ('check.txt', header=FALSE)
colnames(gene_lens)<- c('gene', 'control', 'IP')
print(gene_lens$gene)
par(mar=c(5,4,4,5)+.1)
plot(gene_lens$gene, gene_lens$control, type='h', xlab='base position', ylim=c(0,1000), ylab='read depth', col="skyblue")
par(new=TRUE)
plot(gene_lens$gene, gene_lens$IP, type='h', xlab='base position', ylim=c(0,1000), ylab='read depth', col="red")
legend("topleft",col=c("skyblue","red"),lty=1,legend=c("control","IP"))

But it gives me y axis with 0, 200, 400, 600, 800, 1000. I just want 0, 500, 1000 to be on the scale. (Basically want to reduce the size of the graph). Kindly suggest any edition.

Thanks
Kushal

[jmw86069]

In future, it would be good to post a reproducible example, like including a small dummy data.frame for the "gene_lens" example you described. I made one up just to test, but I have no idea what your real data looks like.
Easiest way to accomplish your goal is to add this to your plot() call:

[COLOR="RoyalBlue"]yaxt="n"[/COLOR]

which will turn off printing the y-axis during the plot() call. Make sure to add it to both plot() commands.
Then use the axis() function with your specific requirements:

axis(2, at=c(0, 500, 1000));

I suggest adding xaxt="n" to the second plot() command, and silencing the second xlab and ylab so they wouldn't double-plot the labels (makes them look bold-pixelated.) Lastly, I didn't know how you intended to handle overlapping lines, so I improvised on line widths so I could see everything. Here is what I came up with:

gene_lens <- data.frame("gene"=c(100,500,750,900),
   "control"=c(10,50,240,890),
   "IP"=c(110,240,830,15));
par("lend"="butt");
plot(gene_lens$gene, gene_lens$control, type='h',
    xlab='base position', ylim=c(0,1000), ylab='read depth',
    col="skyblue3", [COLOR="RoyalBlue"]yaxt="n"[/COLOR], lwd=6);
par("new"=TRUE);
plot(gene_lens$gene, gene_lens$IP, type='h', xlab='',
    ylim=c(0,1000), ylab='', col="red", [COLOR="RoyalBlue"]yaxt="n"[/COLOR],
    xaxt="n", lwd=2);
atN <- c(0, 500, 1000);
axis(2, at=atN, labels=format(atN, big.mark=","), las=2);

I added format() to the axis labels so the numbers are a little friendlier, the "las=2" part to make the axis labels perpendicular to the y-axis. Avoids people having to twist their heads sideways to read the labels. Makes them look like confused puppies. :-)

Lastly, I'm not sure I'm familiar with this type of plot, but it seems like you're going for a sort of bar chart? If so, you may try the barplot2() function in the gplots package, something like this:

library(gplots);
barplot2(t(as.matrix(gene_lens[,c("control", "IP")])), beside=TRUE,
   names.arg=gene_lens$gene, xlab='base position', col=c("seagreen", "orange"),
   yaxt="n", ylim=c(0,1000));
axis(2, las=2, at=c(0,500,1000));