r - Remove facet_wrap labels completely

Question

I'd like to remove the labels for the facets completely to create a sort of sparkline effect, as for the audience the labels are irrelevant, the best I can come up with is:

library(MASS)
library(ggplot2)
qplot(week,y,data=bacteria,group=ID, geom=c('point','line'), xlab='', ylab='') + 
     facet_wrap(~ID) + 
     theme(strip.text.x = element_text(size=0))

So can I get rid of the (now blank) strip.background completely to allow more space for the "sparklines"?

Or alternatively is there a better way to get this "sparkline" effect for a large number of binary valued time-series like this?

Answer 1

For ggplot v2.1.0 or higher, use element_blank() to remove unwanted elements:

library(MASS) # To get the data
library(ggplot2)

qplot(
  week,
  y,
  data = bacteria,
  group = ID,
  geom = c('point', 'line'),
  xlab = '',
  ylab = ''
) + 
facet_wrap(~ ID) + 
theme(
  strip.background = element_blank(),
  strip.text.x = element_blank()
)

In this case, the element you're trying to remove is called strip.

---

Alternative using ggplot grob layout

In older versions of ggplot (before v2.1.0), the strip text occupies rows in the gtable layout.

element_blank removes the text and the background, but it does not remove the space that the row occupied.

This code removes those rows from the layout:

library(ggplot2)
library(grid)

p <- qplot(
  week,
  y,
  data = bacteria,
  group = ID,
  geom = c('point', 'line'),
  xlab = '',
  ylab = ''
) + 
facet_wrap(~ ID)

# Get the ggplot grob
gt <- ggplotGrob(p)

# Locate the tops of the plot panels
panels <- grep("panel", gt$layout$name)
top <- unique(gt$layout$t[panels])

# Remove the rows immediately above the plot panel
gt = gt[-(top-1), ]

# Draw it
grid.newpage()
grid.draw(gt)