Left align two graph edges (ggplot)

Question

I\'m using ggplot and have two graphs that I want to display on top of each other. I used grid.arrange from gridExtra to stack them. The problem is I want the

Answer 1

Here is another possible solution using melt from the reshape2 package, and facet_wrap:

library(ggplot2)
library(reshape2)

dat = CO2[, c(1, 2)]
dat$id = seq(nrow(dat))
mdat = melt(dat, id.vars="id")

head(mdat)
#   id variable value
# 1  1    Plant   Qn1
# 2  2    Plant   Qn1
# 3  3    Plant   Qn1
# 4  4    Plant   Qn1
# 5  5    Plant   Qn1
# 6  6    Plant   Qn1

plot_1 = ggplot(mdat, aes(x=value)) + 
         geom_bar() + 
         coord_flip() +
         facet_wrap(~ variable, nrow=2, scales="free", drop=TRUE)

ggsave(plot=plot_1, filename="plot_1.png", height=4, width=6)

Answer 2

On http://rpubs.com/MarkusLoew/13295 is a really easy solution available (last item) Applied to this problem:

require(ggplot2);require(gridExtra)
A <- ggplot(CO2, aes(x=Plant)) + geom_bar() +coord_flip() 
B <- ggplot(CO2, aes(x=Type)) + geom_bar() +coord_flip() 
grid.draw(rbind(ggplotGrob(A), ggplotGrob(B), size="first"))

you can also use this for both width and height:

require(ggplot2);require(gridExtra)
A <- ggplot(CO2, aes(x=Plant)) + geom_bar() +coord_flip() 
B <- ggplot(CO2, aes(x=Type)) + geom_bar() +coord_flip() 
C <- ggplot(CO2, aes(x=conc)) + geom_bar() +coord_flip()
D <- ggplot(CO2, aes(x=uptake)) + geom_bar() +coord_flip() 
grid.draw(cbind(
            rbind(ggplotGrob(A), ggplotGrob(B), size="first"),
            rbind(ggplotGrob(C), ggplotGrob(D), size="first"),
            size='first'))

Answer 3

The egg package wraps ggplot objects into a standardised 3x3 gtable, enabling the alignment of plot panels between arbitrary ggplots, including facetted ones.

library(egg) # devtools::install_github('baptiste/egg')
library(ggplot2)

p1 <- ggplot(mtcars, aes(mpg, wt, colour = factor(cyl))) +
  geom_point() 

p2 <- ggplot(mtcars, aes(mpg, wt, colour = factor(cyl))) +
  geom_point() + facet_wrap( ~ cyl, ncol=2, scales = "free") +
  guides(colour="none") +
  theme()

ggarrange(p1, p2)

Answer 4

I wanted to generalize this for any number of plots. Here is a step-by-step solution using the approach by Baptiste:

plots <- list(A, B, C, D)
grobs <- list()
widths <- list()

collect the widths for each grob of each plot

for (i in 1:length(plots)){
    grobs[[i]] <- ggplotGrob(plots[[i]])
    widths[[i]] <- grobs[[i]]$widths[2:5]
}

use do.call to get the max width

maxwidth <- do.call(grid::unit.pmax, widths)

asign the max width to each grob

for (i in 1:length(grobs)){
     grobs[[i]]$widths[2:5] <- as.list(maxwidth)
}

plot

do.call("grid.arrange", c(grobs, ncol = 1))

Answer 5

Using cowplot package:

A <- ggplot(CO2, aes(x=Plant)) + geom_bar() +coord_flip() 
B <- ggplot(CO2, aes(x=Type)) + geom_bar() +coord_flip() 

library(cowplot)
plot_grid(A, B, ncol=1, align="v")

Answer 6

At best this is a hack:

library(wq)
layOut(list(A, 1, 2:16),  list(B, 2:3, 1:16))

It feels really wrong though.