# Difference between revisions of "User:Timothee Flutre/Notebook/Postdoc/2011/11/09"

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## Entry title

• in R, replace the row names of a matrix by their new names when the order is different (but assuming one-to-one mapping):
```links <- data.frame(id1=c("a","b","c"), id2=c("1","2","3"), stringsAsFactors=FALSE)
mat <- matrix(runif(3*10), nrow=3)
rownames(mat) <- c("b","c","a")
rownames(mat) <- new.rownames
```

Or it's maybe easier with the built-in match function:

```new.rownames <- links\$id2[ match(rownames(mat), links\$id1) ]
```

• in R, visualize the missing values (encoded as "NA") in a matrix:
```image(1:nrow(mat), 1:ncol(mat), is.na(mat), col=c("white","black"),
main="Missing values", xlab="Genes", ylab="Samples")
```

• in R, customize the built-in heatmap (inspired from this):
```S <- 3  # nb of subgroups
V <- 7  # nb of observations
z <- matrix(c(0,0,0,0,0,0,0,0,0,1,1,1,1,1,1,0,1,1,1,0,0), nrow=V, ncol=S, byrow=TRUE)

myheatmap <- function(z, out.file="") {
par(mar=c(4,5,3,2), font=2, font.axis=2, font.lab=2, cex=1.5, lwd=2)
if (out.file != "")
pdf(out.file)
layout(mat=cbind(1, 2), width=c(7,1))  # plot +  legend
mycol <- rev(heat.colors(4))
image(x=1:NCOL(z), y=1:NROW(z), z=t(z),
xlim=0.5+c(0,NCOL(z)), ylim=0.5+c(0,NROW(z)),
xlab="", ylab="Observations sorted by cluster", main="Custom heatmap",
axes=FALSE, col=mycol)
axis(1, 1:NCOL(z), labels=paste("subgroup", 1:NCOL(z)), tick=0)
par(mar=c(0,0,0,0))
plot.new()
legend("center", legend=sprintf("%.2f", seq(from=min(z), to=max(z), length.out=5)[-1]),
fill=mycol, border=mycol, bty="n")
if (out.file != "")
dev.off()
par(def.par)
}

myheatmap(mydata.sort)
```