Remove blank lines from x axis in ggplot2

Question

I have a some trouble about removing the space in between x axis values. I want to remove the gap between two values in each facet_wrap

I checked this

Answer 1

I had a similar thought to @alistaire but couldn't get ggplot to relinquish enough control, so I went with cowplot::plot_grid().

I rearranged the factors by creating the order manually, with B appearing before A.

df$facet_order <- factor(paste0(df$direc,df$add), levels=c("B1", "A1", "B2", "A2", "B3", "A3", "B4", "A4"))

Creating the plots for A and B individually, then combining them using plot_grid;

g1 <- ggplot(data=df[df$direc=="B",], aes(x=x, y=yy)) +
  geom_point(size=5, col="red") +
  geom_line(size=1.3, col="red") +
  scale_y_log10(limits=c(1e-8,10), breaks = c(3e-7,1e-3,1e-1,1)) +
  scale_x_continuous(expand = c(0, 0),breaks=c(seq(-40,40,10))) +
  facet_wrap(~facet_order, ncol=1) +
  coord_cartesian(xlim=c(-50,0)) + theme(axis.line.x=element_line(colour="red", size=1.5),
                                         legend.position="none")
g2 <- ggplot(data=df[df$direc=="A",], aes(x=x, y=yy)) +
  geom_point(size=5, col="blue") +
  geom_line(size=1.3, col="blue") +
  scale_y_log10(limits=c(1e-8,10), breaks = c(3e-7,1e-3,1e-1,1)) +
  scale_x_continuous(expand = c(0, 0),breaks=c(seq(-40,40,10))) +
  facet_wrap(~facet_order, ncol=1) +
  coord_cartesian(xlim=c(0,50)) + theme(axis.text.y=element_blank(),
                                        axis.line.y=element_blank(),
                                        axis.ticks.y=element_blank(),
                                        axis.title.y=element_blank(), 
                                        axis.line.x=element_line(colour="blue", size=1.5),
                                        legend.position="none")
library(cowplot)
g <- plot_grid(g1,g2,scale=1.05)
g

Depending on the output size you're after, you can mess with the size argument to plot_grid and have the x=0 label exactly overlap so that the data line up perfectly.

My suggestion (in the absence of simply not doing this) would be to do this for all the values of add so that you can manually move the relative x axes so that there is no gap for any of them.

Answer 2

If you turn direc into a factor with levels c('B', 'A') (to arrange facets with B on the left),

df$direc <- factor(direc, levels = c("B", "A"))

just replacing facet_wrap with a facet_grid does the trick.

ggplot(data = df, aes(x = x, y = yy, colour = direc)) +
  geom_point(size=5)+
  geom_line(size=1.3)+
  scale_y_log10(limits = c(1e-7,1),breaks = c(3e-7,1e-3,1e-1,1))+
  facet_grid(add ~ direc, scales = 'free')

Well, a trick; hopefully it's what you want:

The colour argument is also technically unnecessary with this arrangement, though it doesn't cause any issues. I took out scale_x_continuous, as well, because it gets overridden by scales = 'free'.