Align multiple plots in ggplot2 when some have legends and others don't

Question

I have used the method indicated here to align graphs sharing the same abscissa.

But I can\'t make it work when some of my graphs have a legend and others don\'t.

Answer 1

Using grid.arrange

library(ggplot2)
library(reshape2)
library(gridExtra)

x = seq(0, 10, length.out = 200)
y1 = sin(x)
y2 = cos(x)
y3 = sin(x) * cos(x)
df1 <- data.frame(x, y1, y2)
df1 <- melt(df1, id.vars = "x")
g1 <- ggplot(df1, aes(x, value, color = variable)) + geom_line()
df2 <- data.frame(x, y3)
g2 <- ggplot(df2, aes(x, y3)) + geom_line()

#extract the legend from the first graph
temp <- ggplotGrob(g1)
leg_index <- which(sapply(temp$grobs, function(x) x$name) == "guide-box")
legend <- temp$grobs[[leg_index]]

#remove the legend of the first graph
g1 <- g1 + theme(legend.position="none")

#define position of each grobs/plots and width and height ratio
grid_layout <- rbind(c(1,3),
                    c(2,NA))
grid_width <- c(5,1)
grid_heigth <- c(1,1)


grid.arrange(
  grobs=list(g1, g2,legend),
  layout_matrix = grid_layout,
  widths = grid_width,
  heights = grid_heigth)