Removing per-panel unused factors in a bar chart

问题

I am trying to make a plot using barchart from lattice, but I am having some issues with unused factors for a given panel. I have tried using drop.unused.levels but it seems it only drops factors when they are not used in any panel.

This is the data frame that I am using:

dm <- structure(list(Benchmark = structure(c(1L, 2L, 3L, 4L, 5L, 6L, 
7L, 1L, 2L, 3L, 4L, 5L, 6L, 7L, 1L, 2L, 3L, 4L, 5L, 6L, 7L, 1L, 
2L, 3L, 4L, 5L, 6L, 7L, 1L, 2L, 3L, 4L, 5L, 6L, 7L), class = "factor", .Label = c("416.gamess", 
"429.mcf", "436.cactusADM", "458.sjeng", "462.libquantum", "471.omnetpp", 
"482.sphinx3")), Class = structure(c(3L, 1L, 2L, 3L, 1L, 4L, 
2L, 3L, 1L, 2L, 3L, 1L, 4L, 2L, 3L, 1L, 2L, 3L, 1L, 4L, 2L, 3L, 
1L, 2L, 3L, 1L, 4L, 2L, 3L, 1L, 2L, 3L, 1L, 4L, 2L), class = "factor", .Label = c("CS", 
"PF", "PI", "PU")), Config = structure(c(1L, 1L, 1L, 1L, 1L, 
1L, 1L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 
4L, 4L, 4L, 4L, 4L, 4L, 4L, 5L, 5L, 5L, 5L, 5L, 5L, 5L), .Label = c("Disabled", 
"Shallowest", "Deepest", "StorePref", "StridedPref"), class = "factor"), 
    Perf = c(1, 0.72, 0.8, 1, 0.32, 1.16, 0.79, 1, 0.98, 1, 1, 
    0.72, 1, 0.99, 1, 0.98, 1, 1, 1.12, 0.97, 1, 1, 0.97, 1, 
    1, 0.99, 0.97, 1, 1, 1.18, 1, 1, 0.99, 0.97, 1)), .Names = c("Benchmark", 
"Class", "Config", "Perf"), row.names = c(NA, -35L), class = "data.frame")

First I attempted using barchart like this:

barchart(Perf ~ Benchmark | Class, dm, groups=Config,
         scales=list(x=list(relation='free')), auto.key=list(columns=3))

That gave me the following plot:

As you can see, there is a gap between the benchmarks for PI, PF and CS classes. The reason is that each factor is only present in a given class, thus it is missing in all the others, and barchart might introduce a gap in the x axis.

My second attempt was to call barchart four times (one for each class):

class.subset <- function(dframe, class.name) {
    return(dframe[dframe$Class == class.name, ])
}

pl1 <- barchart(Perf ~ Benchmark, class.subset(dm, 'PI'), groups=Config)
pl2 <- barchart(Perf ~ Benchmark, class.subset(dm, 'PF'),, groups=Config)
pl3 <- barchart(Perf ~ Benchmark, class.subset(dm, 'CS'),, groups=Config)
pl4 <- barchart(Perf ~ Benchmark, class.subset(dm, 'PU'),, groups=Config)

print(pl1, split=c(1, 1, 2, 2), more = TRUE)
print(pl2, split=c(1, 2, 2, 2), more = TRUE)
print(pl3, split=c(2, 1, 2, 2), more = TRUE)
print(pl4, split=c(2, 2, 2, 2))

The plot that I got is pretty much what I want, but now I do not know how to create a single global legend for all the subplots (instead of the very same legend for each subplot):

Ideally, I would prefer to solve the problem that I am facing using the first approach (since in that way I would also have the class name in each of the panels). However, if in the second case, it is possible to add a global legend and a title for each subplot containing the class name, that would be okay too.

回答1:

Here's a quick way using latticeExtra:

pl1 <- barchart(Perf ~ Benchmark|Class, class.subset(dm, 'PI'), groups=Config, 
                auto.key=list(columns=3))
pl2 <- barchart(Perf ~ Benchmark|Class, class.subset(dm, 'PF'), groups=Config)
pl3 <- barchart(Perf ~ Benchmark|Class, class.subset(dm, 'CS'), groups=Config)
pl4 <- barchart(Perf ~ Benchmark|Class, class.subset(dm, 'PU'), groups=Config)

library(latticeExtra)
pls <- c(pl1, pl2, pl3, pl4)
pls <- update(pls, scales=list(y="same"))
pls

回答2:

I was just having the same problem in a factor with 95 levels and for lattice::xyplot. What worked for me is (with factor being the variable with too many levels):

    library(gdata)
    key<-simpleKey(levels(drop.levels(df$factor)),...)
    xyplot(response~predictor,groups=factor, data=df, key=key)

Worked like a charm for me. Best wishes!

来源：https://stackoverflow.com/questions/12391429/removing-per-panel-unused-factors-in-a-bar-chart

标签

plot

lattice