CODEWITHSUNDEEP
rggplot2legendlegend-properties
VFreguglia
VFreguglia

Reputation: 2311

ggplot2 legend width and legend strings size

I have 2 plots of the exact same thing, excepts the colors filling the bars are different on each plot. Since the legend on the different plots have different widths because of the size of the names on it, the ratio between graph and legend becomes different on each plot. I need to make both look the same.

This is an example:

library(ggplot2)

x = c(rep("a",20),rep("b",10))
y = c(x = c(rep("BIGTEXT",20),rep("EVENBIGGERTEXT",10)))
df = data.frame(x,y)

p1 = ggplot(df,aes(x,fill=x)) + geom_bar()
p2 = ggplot(df,aes(y,fill=y)) + geom_bar()

p1
p2

Upvotes: 2

Views: 1112

Answers (2)

Sandy Muspratt
Sandy Muspratt

Reputation: 32849

Following up @baptiste's comment: Fiddly but yes, it can be done. But no guarantees that this will work in future versions. The solution was taken from here, but that solution too needed updating.

library(ggplot2)   # v2.2.1
library(gtable)    # v0.2.0
library(grid)
library(gridExtra) # v2.2.1

x = c(rep("a",20),rep("b",10))
y = c(x = c(rep("BIGTEXT",20),rep("EVENBIGGERTEXT",10)))
df = data.frame(x,y)

p1 = ggplot(df,aes(x,fill=x)) + geom_bar()
p2 = ggplot(df,aes(y,fill=y)) + geom_bar()

# Get the grobs
gA <- ggplotGrob(p1)
gB <- ggplotGrob(p2)

# Get the widths of the legends
index = which(gA$layout$name == "guide-box")
leg1 <- convertX(sum(with(gA$grobs[[index]], grobs[[1]]$widths)), "mm")
leg2 <- convertX(sum(with(gB$grobs[[index]], grobs[[1]]$widths)), "mm")

# Add an empty column of width "abs(diff(c(leg1, leg2))) mm" to the right of 
# legend box for gA (the smaller legend box)
gA$grobs[[index]] <- gtable_add_cols(gA$grobs[[index]], unit(abs(diff(c(leg1, leg2))), "mm"))

# Set widths to maximums of corresponding widths
gl <- list(gA, gB)
gwidth <- do.call(unit.pmax, lapply(gl, "[[", "widths"))
gl <- lapply(gl, "[[<-", "widths", value = gwidth)


# Draw the plots
grid.newpage()
grid.draw(gl[[1]])

grid.newpage()
grid.draw(gl[[2]])

Upvotes: 0

baptiste
baptiste

Reputation: 77116

You can set the gtable widths to a common value,

library(gtable)
library(grid)
gl <- lapply(list(p1, p2), ggplotGrob)

gwidth <- do.call(unit.pmax, lapply(gl, "[[", "widths"))
gl <- lapply(gl, "[[<-", "widths", value = gwidth)
gridExtra::grid.arrange(grobs=gl)

Alternatively, you can set the panel size to a fixed value.

Upvotes: 3

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