Reputation: 10215
A ggplot2-challenged latticist needs help: What's the syntax to request variable per-facet breaks in a histogram?
library(ggplot2)
d = data.frame(x=c(rnorm(100,10,0.1),rnorm(100,20,0.1)),par=rep(letters[1:2],each=100))
# Note: breaks have different length by par
breaks = list(a=seq(9,11,by=0.1),b=seq(19,21,by=0.2))
ggplot(d, aes(x=x) ) +
geom_histogram() + ### Here the ~breaks should be added
facet_wrap(~ par, scales="free")
As pointed out by jucor, here some more solutions.
On special request, and to show why I am not a great ggplot fan, the lattice
version
library(lattice)
d = data.frame(x=c(rnorm(100,10,0.1),rnorm(100,20,0.1)),par=rep(letters[1:2],each=100))
# Note: breaks have different length by par
myBreaks = list(a=seq(8,12,by=0.1),b=seq(18,22,by=0.2))
histogram(~x|par,data=d,
panel = function(x,breaks,...){
# I don't know of a generic way to get the
# grouping variable with histogram, so
# this is not very generic
par = levels(d$par)[which.packet()]
breaks = myBreaks[[par]]
panel.histogram(x,breaks=breaks,...)
},
breaks=NULL, # important to force per-panel compute
scales=list(x=list(relation="free")))
Upvotes: 22
Views: 9420
Reputation: 25914
Following on from Didzis example:
ggplot(dat=d, aes(x=x, y=..ncount..)) +
geom_histogram(data = d[d$par == "a",], binwidth=0.1) +
geom_histogram(data = d[d$par == "b",], binwidth=0.01) +
facet_grid(.~ par, scales="free")
EDIT: This works for more levels but of course there are already better solutions
# More facets
d <- data.frame(x=c(rnorm(200,10,0.1),rnorm(200,20,0.1)),par=rep(letters[1:4],each=100))
# vector of binwidths same length as number of facets - need a nicer way to calculate these
my.width=c(0.5,0.25,0.1,0.01)
out<-lapply(1:length(my.width),function(.i) data.frame(par=levels(d$par)[.i],ggplot2:::bin(d$x[d$par==levels(d$par)[.i]],binwidth=my.width[.i])))
my.df<-do.call(rbind , out)
ggplot(my.df) + geom_histogram(aes(x, y = density, width = width), stat = "identity") + facet_wrap(~par,scales="free")
from https://groups.google.com/forum/?fromgroups=#!searchin/ggplot2/bin$20histogram$20by$20facet/ggplot2/xlqRIFPP-zE/CgfigIkgAAkJ
Upvotes: 4
Reputation: 58845
It is not, strictly speaking, possible to give different breaks in the different facets. But you can get the same effect by having a different layer for each facet (much as in user20650's answer), but mostly automating the multiple geom_histogram
calls:
d <- data.frame(x=c(rnorm(100,10,0.1),rnorm(100,20,0.1)),
par=rep(letters[1:2],each=100))
breaks <- list(a=seq(9,11,by=0.1),b=seq(19,21,by=0.2))
ggplot(d, aes(x=x)) +
mapply(function(d, b) {geom_histogram(data=d, breaks=b)},
split(d, d$par), breaks) +
facet_wrap(~ par, scales="free_x")
The mapply
call creates a list of geom_histogram
s which can be added to the plot. The tricky part is that you have to manually split the data (split(d, d$par)
) into the data that goes into each facet.
Upvotes: 3
Reputation: 66902
Here is one alternative:
hls <- mapply(function(x, b) geom_histogram(data = x, breaks = b),
dlply(d, .(par)), myBreaks)
ggplot(d, aes(x=x)) + hls + facet_wrap(~par, scales = "free_x")
If you need to shrink the range of x, then
hls <- mapply(function(x, b) {
rng <- range(x$x)
bb <- c(rng[1], b[rng[1] <= b & b <= rng[2]], rng[2])
geom_histogram(data = x, breaks = bb, colour = "white")
}, dlply(d, .(par)), myBreaks)
ggplot(d, aes(x=x)) + hls + facet_wrap(~par, scales = "free_x")
Upvotes: 18
Reputation: 98579
I don't think that it is possible to give different break points in each facet.
As workaround you can make two plots and then with grid.arrange()
function from library gridExtra
put them together. To set break points in geom_histogram()
use binwidth=
and set one value for width of bin.
p1<-ggplot(subset(d,par=="a"), aes(x=x) ) +
geom_histogram(binwidth=0.1) +
facet_wrap(~ par)
p2<-ggplot(subset(d,par=="b"), aes(x=x) ) +
geom_histogram(binwidth=0.2) +
facet_wrap(~ par)
library(gridExtra)
grid.arrange(p1,p2,ncol=2)
Upvotes: 5