Moving x or y axis together with tick labels to the middle of a single ggplot (no facets)

Question

I made the following plot in Excel:

But then I thought I would make it prettier by using ggplot. I got this far:

If you're curious, the data is based on my answer here, although it doesn't really matter. The plot is a standard ggplot2 construct with some prettification, and the thick line for the x-axis through the middle is achieved with p + geom_hline(aes(yintercept=0)) (p is the ggplot object).

I feel that the axis configuration in the Excel plot is better. It emphasizes the 0 line (important when the data is money) and finding intercepts is much easier since you don't have to follow lines from all the way at the bottom. This is also how people draw axes when plotting on paper or boards.

Can the axis be moved like this in ggplot as well? I want not just the line, but the tick labels as well moved. If yes, how? If no, is the reason technical or by design? If by design, why was the decision made?

Gloriole

You could fake it with geom_hline, geom_text, and geom_segment. Also, if I need USD $700 million to retire, I should give up now. – Spaceship

But look how fast it is spent. All gone by 70. Quite the retirement. – Undercut

Just write your own dollar value appropriate theme or see here. #21027098 – Undercut

#36677378 should help – Lennie

Huh? "Can the axis be moved like this in ggplot"? What pray tell does that actually mean? – Cartan

Answer 1

try this,

shift_axis <- function(p, y=0){
  g <- ggplotGrob(p)
  dummy <- data.frame(y=y)
  ax <- g[["grobs"]][g$layout$name == "axis-b"][[1]]
  p + annotation_custom(grid::grobTree(ax, vp = grid::viewport(y=1, height=sum(ax$height))), 
                        ymax=y, ymin=y) +
    geom_hline(aes(yintercept=y), data = dummy) +
    theme(axis.text.x = element_blank(), 
          axis.ticks.x=element_blank())

}

p <- qplot(1:10, 1:10) + theme_bw() 
shift_axis(p, 5)

Pervade

Answer 2

I tried to change the theme's axis.text.x,but only can change hjust.
So I think you can delete axis.text.x,then use geom_text() to add.
For example:

test <- data.frame(x=seq(1,5), y=seq(-1,3))
ggplot(data=test, aes(x,y)) +
  geom_line() +
  theme(axis.text.x=element_blank(), axis.ticks.x=element_blank()) +
  geom_text(data=data.frame(x=seq(1,5), y=rep(0,5)), label=seq(1,5), vjust=1.5)

Maybe these codes are useful.

Embouchure

Answer 3

just to complete baptiste's excellent answer with the equivalent for moving the y axis:

shift_axis_x <- function(p, x=0){
      g <- ggplotGrob(p)
      dummy <- data.frame(x=x)
      ax <- g[["grobs"]][g$layout$name == "axis-l"][[1]]
      p + annotation_custom(grid::grobTree(ax, vp = grid::viewport(x=1, width = sum(ax$height))), 
                            xmax=x, xmin=x) +
        geom_vline(aes(xintercept=x), data = dummy) +
        theme(axis.text.y = element_blank(), 
              axis.ticks.y=element_blank())
    }

Hepatica

Answer 4

As alistaire commented it can be done using geom_hline and geom_text as shown below.

df <- data.frame(YearMonth = c(200606,200606,200608,200701,200703,200605),
             person1 = c('Alice','Bob','Alice','Alice','Bob','Alice'),
             person2 = c('Bob','Alice','Bob','Bob','Alice','Bob'),
             Event = c('event1','event2','event3','event3','event2','event4')
)

df$YM <- as.Date(paste0("01",df$YearMonth), format="%d%Y%m")
rangeYM <- range(df$YM)

ggplot()+geom_blank(aes(x= rangeYM, y = c(-1,1))) + labs(x = "", y = "") +
theme(axis.ticks = element_blank()) +
geom_hline(yintercept = 0, col = 'maroon') +
scale_x_date(date_labels = '%b-%y', date_breaks = "month", minor_breaks = NULL) +
scale_y_continuous(minor_breaks = NULL) +
geom_text(aes(x = df$YM, y = 0, label = paste(format(df$YM, "%b-%y")), vjust = 1.5), colour = "#5B7FA3", size = 3.5, fontface = "bold") 

Hydride