heatmap.2

Enhanced Heat Map

A heat map is a false color image (basically image(t(x))) with a dendrogram added to the left side and/or to the top. Typically, reordering of the rows and columns according to some set of values (row or column means) within the restrictions imposed by the dendrogram is carried out.

This heatmap provides a number of extensions to the standard R heatmap function.

Usage

heatmap.2 (x,
           # dendrogram control Rowv = TRUE, Colv=if(symm)"Rowv" else TRUE, distfun = dist, hclustfun = hclust, dendrogram = c("both","row","column","none"), reorderfun = function(d, w) reorder(d, w), symm = FALSE,
           # data scaling scale = c("none","row", "column"), na.rm=TRUE,
           # image plot revC = identical(Colv, "Rowv"), add.expr,
           # mapping data to colors breaks, symbreaks=any(x < 0, na.rm=TRUE) || scale!="none",
           # colors col="heat.colors",
           # block sepration colsep, rowsep, sepcolor="white", sepwidth=c(0.05,0.05),
           # cell labeling cellnote, notecex=1.0, notecol="cyan", na.color=par("bg"),
           # level trace trace=c("column","row","both","none"), tracecol="cyan", hline=median(breaks), vline=median(breaks), linecol=tracecol,
           # Row/Column Labeling margins = c(5, 5), ColSideColors, RowSideColors, cexRow = 0.2 + 1/log10(nr), cexCol = 0.2 + 1/log10(nc), labRow = NULL, labCol = NULL, srtRow = NULL, srtCol = NULL, adjRow = c(0,NA), adjCol = c(NA,0), offsetRow = 0.5, offsetCol = 0.5, colRow = NULL, colCol = NULL,
           # color key + density info key = TRUE, keysize = 1.5, density.info=c("histogram","density","none"), denscol=tracecol, symkey = any(x < 0, na.rm=TRUE) || symbreaks, densadj = 0.25, key.title = NULL, key.xlab = NULL, key.ylab = NULL, key.xtickfun = NULL, key.ytickfun = NULL, key.par=list(),
           # plot labels main = NULL, xlab = NULL, ylab = NULL,
           # plot layout lmat = NULL, lhei = NULL, lwid = NULL,
           # extras extrafun=NULL, ... )

Details

If either Rowv or Colv are dendrograms they are honored (and not reordered). Otherwise, dendrograms are computed as dd <- as.dendrogram(hclustfun(distfun(X))) where X is either x or t(x).

If either is a vector (of “weights”) then the appropriate dendrogram is reordered according to the supplied values subject to the constraints imposed by the dendrogram, by reorder(dd, Rowv), in the row case. If either is missing, as by default, then the ordering of the corresponding dendrogram is by the mean value of the rows/columns, i.e., in the case of rows, Rowv <- rowMeans(x, na.rm=na.rm). If either is NULL, no reordering will be done for the corresponding side.

If scale="row" (or scale="col") the rows (columns) are scaled to have mean zero and standard deviation one. There is some empirical evidence from genomic plotting that this is useful.

The default colors range from red to white (heat.colors) and are not pretty. Consider using enhancements such as the RColorBrewer package, https://cran.r-project.org/package=RColorBrewer to select better colors.

By default four components will be displayed in the plot. At the top left is the color key, top right is the column dendrogram, bottom left is the row dendrogram, bottom right is the image plot. When RowSideColor or ColSideColor are provided, an additional row or column is inserted in the appropriate location. This layout can be overriden by specifiying appropriate values for lmat, lwid, and lhei. lmat controls the relative postition of each element, while lwid controls the column width, and lhei controls the row height. See the help page for layout for details on how to use these arguments.

Note

The original rows and columns are reordered to match the dendrograms Rowv and Colv (if present).

heatmap.2() uses layout to arragent the plot elements. Consequentially, it can not be used in a multi column/row layout using layout(...), par(mfrow=...) or (mfcol=...).

See Also

image, hclust

Aliases

• heatmap.2

Examples

 data(mtcars)
 x  <- as.matrix(mtcars)
 rc <- rainbow(nrow(x), start=0, end=.3)
 cc <- rainbow(ncol(x), start=0, end=.3)

 ##
 ## demonstrate the effect of row and column dendrogram options
 ##
 heatmap.2(x)                    ## default - dendrogram plotted and reordering done.
 heatmap.2(x, dendrogram="none") ##  no dendrogram plotted, but reordering done.
 heatmap.2(x, dendrogram="row")  ## row dendrogram plotted and row reordering done.
 heatmap.2(x, dendrogram="col")  ## col dendrogram plotted and col reordering done.

 heatmap.2(x, keysize=2)         ## default - dendrogram plotted and reordering done.

 heatmap.2(x, Rowv=FALSE, dendrogram="both") ## generates a warning!
 heatmap.2(x, Rowv=NULL, dendrogram="both")  ## generates a warning!
 heatmap.2(x, Colv=FALSE, dendrogram="both") ## generates a warning!

 ## Reorder dendrogram by branch means rather than sums
 heatmap.2(x, reorderfun=function(d, w) reorder(d, w, agglo.FUN = mean) )

 ## plot a sub-cluster using the same color coding as for the full heatmap
 full <- heatmap.2(x)
 heatmap.2(x, Colv=full$colDendrogram[[2]], breaks=full$breaks)  # column subset
 heatmap.2(x, Rowv=full$rowDendrogram[[1]], breaks=full$breaks)  # row subset
 heatmap.2(x, Colv=full$colDendrogram[[2]],
              Rowv=full$rowDendrogram[[1]], breaks=full$breaks)  # both

 ## Show effect of row and column label rotation
 heatmap.2(x, srtCol=NULL)
 heatmap.2(x, srtCol=0,   adjCol = c(0.5,1) )
 heatmap.2(x, srtCol=45,  adjCol = c(1,1)   )
 heatmap.2(x, srtCol=135, adjCol = c(1,0)   )
 heatmap.2(x, srtCol=180, adjCol = c(0.5,0) )
 heatmap.2(x, srtCol=225, adjCol = c(0,0)   ) ## not very useful
 heatmap.2(x, srtCol=270, adjCol = c(0,0.5) )
 heatmap.2(x, srtCol=315, adjCol = c(0,1)   )
 heatmap.2(x, srtCol=360, adjCol = c(0.5,1) )

 heatmap.2(x, srtRow=45, adjRow=c(0, 1) )
 heatmap.2(x, srtRow=45, adjRow=c(0, 1), srtCol=45, adjCol=c(1,1) )
 heatmap.2(x, srtRow=45, adjRow=c(0, 1), srtCol=270, adjCol=c(0,0.5) )


 ## Show effect of offsetRow/offsetCol (only works when srtRow/srtCol is
 ## not also present)
 heatmap.2(x, offsetRow=0, offsetCol=0)
 heatmap.2(x, offsetRow=1, offsetCol=1)
 heatmap.2(x, offsetRow=2, offsetCol=2)
 heatmap.2(x, offsetRow=-1, offsetCol=-1)

 heatmap.2(x, srtRow=0, srtCol=90, offsetRow=0, offsetCol=0)
 heatmap.2(x, srtRow=0, srtCol=90, offsetRow=1, offsetCol=1)
 heatmap.2(x, srtRow=0, srtCol=90, offsetRow=2, offsetCol=2)
 heatmap.2(x, srtRow=0, srtCol=90, offsetRow=-1, offsetCol=-1)


 ## Show how to use 'extrafun' to replace the 'key' with a scatterplot
 lmat <- rbind( c(5,3,4), c(2,1,4) )
 lhei <- c(1.5, 4)
 lwid <- c(1.5, 4, 0.75)

 myplot <- function() {
             oldpar <- par("mar")
             par(mar=c(5.1, 4.1, 0.5, 0.5))
             plot(mpg ~ hp, data=x)
           }

 heatmap.2(x, lmat=lmat, lhei=lhei, lwid=lwid, key=FALSE, extrafun=myplot)

 ## show how to customize the color key
 heatmap.2(x,
           key.title=NA, # no title
           key.xlab=NA,  # no xlab
           key.par=list(mgp=c(1.5, 0.5, 0),
                        mar=c(2.5, 2.5, 1, 0)),
           key.xtickfun=function() {
                 breaks <- parent.frame()$breaks
                 return(list(
                      at=parent.frame()$scale01(c(breaks[1],
                                                  breaks[length(breaks)])),
                      labels=c(as.character(breaks[1]),
                               as.character(breaks[length(breaks)]))
                      ))
           })

 heatmap.2(x,
          breaks=256,
          key.title=NA,
          key.xlab=NA,
          key.par=list(mgp=c(1.5, 0.5, 0),
                       mar=c(1, 2.5, 1, 0)),
          key.xtickfun=function() {
               cex <- par("cex")*par("cex.axis")
               side <- 1
               line <- 0
               col <- par("col.axis")
               font <- par("font.axis")
               mtext("low", side=side, at=0, adj=0,
                     line=line, cex=cex, col=col, font=font)
               mtext("high", side=side, at=1, adj=1,
                     line=line, cex=cex, col=col, font=font)
               return(list(labels=FALSE, tick=FALSE))
          })


 ##
 ## Show effect of z-score scaling within columns, blue-red color scale
 ##
 hv <- heatmap.2(x, col=bluered, scale="column", tracecol="#303030")

 ###
 ## Look at the return values
 ###
 names(hv)

 ## Show the mapping of z-score values to color bins
 hv$colorTable

 ## Extract the range associated with white
 hv$colorTable[hv$colorTable[,"color"]=="#FFFFFF",]

 ## Determine the original data values that map to white
 whiteBin <- unlist(hv$colorTable[hv$colorTable[,"color"]=="#FFFFFF",1:2])
 rbind(whiteBin[1] * hv$colSDs + hv$colMeans,
       whiteBin[2] * hv$colSDs + hv$colMeans )
 ##
 ## A more decorative heatmap, with z-score scaling along columns
 ##
 hv <- heatmap.2(x, col=cm.colors(255), scale="column",
	       RowSideColors=rc, ColSideColors=cc, margin=c(5, 10),
	       xlab="specification variables", ylab= "Car Models",
	       main="heatmap(<Mtcars data>, ..., scale=\"column\")",
         tracecol="green", density="density")
 ## Note that the breakpoints are now symmetric about 0

 ## Color the labels to match RowSideColors and ColSideColors
 hv <- heatmap.2(x, col=cm.colors(255), scale="column",
         RowSideColors=rc, ColSideColors=cc, margin=c(5, 10),
	       xlab="specification variables", ylab= "Car Models",
	       main="heatmap(<Mtcars data>, ..., scale=\"column\")",
         tracecol="green", density="density", colRow=rc, colCol=cc,
         srtCol=45, adjCol=c(0.5,1))





 data(attitude)
 round(Ca <- cor(attitude), 2)
 symnum(Ca) # simple graphic

 # with reorder
 heatmap.2(Ca, 		 symm=TRUE, margin=c(6, 6), trace="none" )

 # without reorder
 heatmap.2(Ca, Rowv=FALSE, symm=TRUE, margin=c(6, 6), trace="none" )

 ## Place the color key below the image plot
 heatmap.2(x, lmat=rbind( c(0, 3), c(2,1), c(0,4) ), lhei=c(1.5, 4, 2 ) )

 ## Place the color key to the top right of the image plot
 heatmap.2(x, lmat=rbind( c(0, 3, 4), c(2,1,0 ) ), lwid=c(1.5, 4, 2 ) )

 ## For variable clustering, rather use distance based on cor():
 data(USJudgeRatings)
 symnum( cU <- cor(USJudgeRatings) )

 hU <- heatmap.2(cU, Rowv=FALSE, symm=TRUE, col=topo.colors(16),
              distfun=function(c) as.dist(1 - c), trace="none")

 ## The Correlation matrix with same reordering:
 hM <- format(round(cU, 2))
 hM

 # now with the correlation matrix on the plot itself

 heatmap.2(cU, Rowv=FALSE, symm=TRUE, col=rev(heat.colors(16)),
             distfun=function(c) as.dist(1 - c), trace="none",
             cellnote=hM)

 ## genechip data examples
 ## Not run: 
#  library(affy)
#  data(SpikeIn)
#  pms <- SpikeIn@pm
# 
#  # just the data, scaled across rows
#  heatmap.2(pms, col=rev(heat.colors(16)), main="SpikeIn@pm",
#               xlab="Relative Concentration", ylab="Probeset",
#               scale="row")
# 
#  # fold change vs "12.50" sample
#  data <- pms / pms[, "12.50"]
#  data <- ifelse(data>1, data, -1/data)
#  heatmap.2(data, breaks=16, col=redgreen, tracecol="blue",
#                main="SpikeIn@pm Fold Changes\nrelative to 12.50 sample",
#                xlab="Relative Concentration", ylab="Probeset")
#  ## End(Not run)