# User:Timothee Flutre/Notebook/Postdoc/2011/11/09

(Difference between revisions)
 Revision as of 19:49, 9 November 2011 (view source) (→Entry title: visualize NA in matrix)← Previous diff Revision as of 13:18, 10 November 2011 (view source) (→Entry title: use R built-in "match")Next diff → Line 16: Line 16: rownames(mat) <- new.rownames rownames(mat) <- new.rownames - Or it's maybe easier with the built-in [http://stat.ethz.ch/R-manual/R-patched/library/base/html/replace.html replace] function. + Or it's maybe easier with the built-in [http://stat.ethz.ch/R-manual/R-patched/library/base/html/match.html match] function: + + new.rownames <- links\$id2[ match(rownames(mat), links\$id1) ]

## Revision as of 13:18, 10 November 2011

Project name Main project page
Previous entry      Next entry

## 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")
```