CODEWITHSUNDEEP
rggplot2heatmap
dli
dli

Reputation: 1213

align color blocks in ggplot2 heatmap

I am using ggplot2 to draw a heatmap with a few color blocks in each line. Like this:

enter image description here

Basically each row will have 200 numbers represent 200 bins, each bin would either have number 1, 2, 3 and 4, which correspond to white, red, blue and orange color.

What I want to do is to align the red block to same column vertically, which means for other rows, have to apply an x-axis offset.

I am using ggplot2 and qplot for this figure, did anyone know how to do the alignment? Thanks a lot.

The code to produce this figure:

library(ggplot2)
library(reshape2)
dat <- read.table('http://wangftp.wustl.edu/~dli/fimo.near.3ins', header=FALSE)
dat$V2 <- factor(dat$V2)
dat.m <- melt(dat, id.vars=c("V1","V2"))
col2=c('white','red','blue','orange')
qplot(variable, V1, fill=col2[value], data=dat.m, geom="tile") + theme_bw() + scale_fill_identity(breaks=col2, guide="legend") + theme(axis.title.x = element_blank(), axis.text.x = element_blank(), axis.text.y = element_blank(), axis.title.y = element_blank(), legend.title = element_text(size=18), legend.text = element_text(size=16),axis.ticks.x = element_blank(),axis.ticks.y = element_blank(), panel.grid=element_blank()) + geom_hline(aes(yintercept=V1))

Upvotes: 0

Views: 793

Answers (1)

MrFlick
MrFlick

Reputation: 206232

This is even a bit more tricky because your x-axis values are factors rather than simple numeric values. But as I thought, the only way to really accomplish this is to transform your data. We need to create a new vector shared across all rows to coordinate placement of start of the orange boxes. Here we first calculate the distance of each box from the start of the orange box for each group

offset<-with(dat.m, ave(value, V1, 
    FUN=function(x) seq_along(x)-head(which(x==4),1)))

Now we create a new factor variable in the appropriate order for the offset

dat.m$opos<-factor(offset, levels=seq(from=min(offset),to=max(offset)))

Now we simply plot using this as the x value

qplot(opos, V1, fill=col2[value], data=dat.m, geom="tile") + ...

Comparing this to the original, we see the following plot

comparison of before and after

The boxes seem a bit more narrow because we've essentially zoomed out to see more of all the regions.

Upvotes: 1

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