Manhattan plot with annotations

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Description

To generate Manhattan plot with annotations. The function is generic and for instance could be used for genomewide p values or any random variable that is uniformly distributed. By default, a log10-transformation is applied. Note that with real chromosomal positions, it is also appropriate to plot and some but not all chromosomes.

It is possible to specify options such as xlab, ylim and font family when the plot is requested for data in other context.

To maintain back compatibility options as in mhtplot are used. The positions of the horizontal labels are now in the middle rather than at the beginning of their bands in the plot.

Usage

1
mhtplot2(data, control=mht.control(), hcontrol=hmht.control(), ...)

Arguments

data

a data frame with three columns representing chromosome, position and p values

control

A control function named mht.control() with the following arguments,

  1. type. a flag with value "p" or "l" indicating if points or lines are to be drawn.

  2. usepos. a flag to use real chromosomal positions as composed to ordinal positions with default value FALSE

  3. logscale. a flag to indicate if p value is to be log-transformed with default value TRUE

  4. base. the base of the logarithm with default value 10

  5. cutoffs. the cut-offs where horizontal line(s) are drawn with default value NULL

  6. colors. the color for different chromosome(s), and random if unspecified with default values NULL

  7. labels. labels for the ticks on x-axis with default value NULL

  8. srt. degree to which labels are rotated with default value of 45

  9. gap. gap between chromosomes with default value NULL

  10. cex. cex for the data points

  11. yline. Margin line position

  12. xline. Margin line position

hcontrol

A control function named hmht.control() with the following arguments,

  1. data. chunk of data to be highlighted with default value NULL

  2. colors. colors for annotated genes

  3. yoffset. offset above the data point showing most significant p value with default value 0.5

  4. cex. shrinkage factor for data points with default value 1.5

  5. boxed. if the label for the highlited region with default value FALSE

...

other options in compatible with the R plot function

Value

The plot is shown on or saved to the appropriate device.

References

den Hoed M, et al. (2013). Heart rate-associated loci and their effects on cardiac conduction and rhythm disorders. Nat Genet 45:621-631

Author(s)

Jing Hua Zhao

Examples

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## Not run: 
# The following example uses only chromosomes 14 and 20 of the Nat Genet paper.
#
mdata <- within(hr1420,{
  c1<-colour==1
  c2<-colour==2
  c3<-colour==3
  colour[c1] <- 62
  colour[c2] <- 73
  colour[c3] <- 552
})
mdata <- mdata[,c("CHR","POS","P","gene","colour")]
ops <- mht.control(colors=rep(c("lightgray","gray"),11),yline=1.5,xline=2,srt=0)
hops <- hmht.control(data=subset(mdata,!is.na(gene)))
v <- "Verdana"
ifelse(Sys.info()['sysname']=="Windows", windowsFonts(ffamily=windowsFont(v)),
       ffamily <- v)
tiff("mh.tiff", width=.03937*189, height=.03937*189/2, units="in", res=1200,
     compress="lzw")
par(las=2, xpd=TRUE, cex.axis=1.8, cex=0.4)
mhtplot2(with(mdata,cbind(CHR,POS,P,colour)),ops,hops,pch=19,
         ylab=expression(paste(plain("-"),log[10],plain("p-value"),sep=" ")),
         family="ffamily")
axis(2,pos=2,at=seq(0,25,5),family="ffamily",cex=0.5,cex.axis=1.1)
dev.off()

# To exemplify the use of chr, pos and p without gene annotation
# in response to query from Vallejo, Roger <Roger.Vallejo@ARS.USDA.GOV>
opar <- par()
par(cex=0.4)
ops <- mht.control(colors=rep(c("lightgray","lightblue"),11),srt=0,yline=2.5,xline=2)
mhtplot2(data.frame(mhtdata[,c("chr","pos","p")],gene=NA,color=NA),ops,xlab="",ylab="",srt=0)
axis(2,at=1:16)
title("data in mhtplot used by mhtplot2")                 
par(opar)

## End(Not run)

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