# Easy pictograms using R

**Robert Grant's stats blog » R**, and kindly contributed to R-bloggers]. (You can report issue about the content on this page here)

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I have been amazed for a while that there is no major stats software offering pictograms. You know the sort of classic infographic I mean:

Well, I have been working on an R function to help with this. It’s at Github here and below. Here’s an example:

`man<-readPNG("man.png")`

```
pictogram(icon=man,
n=c(12,35,52),
grouplabels=c("dudes","chaps","lads"))
```

Simple, huh? You can also have more than one icon, although it’s up to you to keep them a sensible height:width ratio or ‘aspect’ to avoid distorting impressions.

```
pictogram(icon=list(man,holly,monster),
n=c(12,35,52),
grouplabels=c("men","holly","monsters"))
```

Suggestions? e-mail me or better still, pull them on Github. Happy pictogramming!

```
# requires image to be read in by readPNG or similar and supplied as "icon"
# To do: allow for non-integer n
pictogram<-function(icon,n,grouplabels="",
hicons=20,vspace=0.5,labprop=0.2,labelcex=1) {
if(is.list(icon)) {
licon<-icon
} else {
licon<-list(icon)
for (i in 2:length(n)) {
licon[[i]]<-icon
}
}
library(reshape)
sumn<-sum(n)
group<-untable(df=matrix((1:length(n)),ncol=1),num=n)
vicons<-ceiling(n/hicons)
allv<-sum(vicons)
tail<-n%%hicons
# dim[1] is the height, dim[2] the width:
devaspect<-dev.size(units="px")[1]/dev.size(units="px")[2]
xlength<-1
# get dims of all elements of licon, find greatest aspect and set ylength
getdim<-function(z) {
aspect<-dim(z)[1]/dim(z)[2]
return(aspect)
}
all.ylengths<-unlist(lapply(licon,getdim))
ylength<-max(all.ylengths)
all.ylengths<-untable(df=matrix(all.ylengths,ncol=1),num=n)
ytop<-allv*ylength
if(devaspect*hicons<allv) warning("Icons may extend above the top of the graph")
# vector of icons per row
iconrow<-as.vector(as.matrix(rbind(rep(hicons,length(vicons)),tail)))
# vector for how many times to repeat elements of iconrow
reprow<-as.vector(as.matrix(rbind((vicons-1),rep(1,length(vicons)))))
perrow<-untable(df=matrix(iconrow,ncol=1),num=reprow)
spacing<-NULL
for (i in 1:(length(n))) {
spacing<-c(spacing,rep((i-1)*vspace*ylength,n[i]))
}
y0<-spacing+(ylength*untable(df=matrix((1:allv)-1,ncol=1),num=perrow))
y1<-y0+all.ylengths
# there are more elegant ways to make x0, but for now...
x0<-NULL
for (i in 1:(length(perrow))) {
x0<-c(x0,(0:(perrow[i]-1)))
}
x1<-x0+xlength
leftplot<-floor(-(labprop*hicons))
plot(c(leftplot,hicons),c(0,(devaspect*hicons)),
type="n",bty="n",ylab="",xlab="",xaxt="n",yaxt="n")
lines(x=c(0,0),y=c(min(y0)-(ylength/2),max(y1)+(ylength/2)))
for (i in 1:sumn) {
rasterImage(image=licon[[group[i]]],xleft=x0[i],xright=x1[i],
ytop=y1[i],ybottom=y0[i])
}
# find positions for labels
ylabpos<-rep(NA,length(n))
for (i in 1:length(n)) {
ylabpos[i]<-(max(y1[group==i])+min(y0[group==i]))/2
}
text(x=leftplot/2,y=ylabpos,labels=grouplabels,cex=labelcex)
}
```

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**Robert Grant's stats blog » R**.

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