Strip placement (bottom, outside) and empty slots

[zz77zz]

---

[issue raised at https://stackoverflow.com/questions/50385053/ggplot2-unexpected-vapply-error]

In some situations, empty slots in a row together with the "bottom" parameter lead to the following error:

"Error in vapply(row_axes, is.zero, logical(length(row_axes))) : values must be length 3, but FUN(X[[1]]) result is length 1"

library(ggplot2)

zzz <- data.frame(gp = c("a","b","c","d","e","f","g"), 
                  c1 = c(1,1,1,1,1,1,1), 
                  c2 = c(1,1,1,1,1,1,1))

ggplot(zzz, aes(x = c1, y = c2)) +
  facet_wrap(~ gp, scales = "free", nrow = 3, strip.position = "bottom") +
  geom_point() +
  theme(
    aspect.ratio = 1,
    strip.background = element_blank(),
    strip.placement = "outside"
  )

[batpigandme]

reprex with working example without strip.position = "bottom" and one with strip.position = "left" (works with others as well):

library(ggplot2)

zzz <- data.frame(gp = c("a","b","c","d","e","f","g"), 
                  c1 = c(1,1,1,1,1,1,1), 
                  c2 = c(1,1,1,1,1,1,1))

# without strip position argument
ggplot(zzz, aes(x = c1, y = c2)) +
  facet_wrap(~ gp, scales = "free", nrow = 3) +
  geom_point() +
  theme(
    aspect.ratio = 1,
    strip.background = element_blank(),
    strip.placement = "outside"
  )

ggplot(zzz, aes(x = c1, y = c2)) +
  facet_wrap(~ gp, scales = "free", nrow = 3, strip.position = "bottom") +
  geom_point() +
  theme(
    aspect.ratio = 1,
    strip.background = element_blank(),
    strip.placement = "outside"
  )
#> Error in vapply(row_axes, is.zero, logical(length(row_axes))): values must be length 2,
#>  but FUN(X[[1]]) result is length 1

# works for other positions
ggplot(zzz, aes(x = c1, y = c2)) +
  facet_wrap(~ gp, scales = "free", nrow = 3, strip.position = "left") +
  geom_point() +
  theme(
    aspect.ratio = 1,
    strip.background = element_blank(),
    strip.placement = "outside"
  )

Created on 2018-05-17 by the reprex package (v0.2.0).

[batpigandme]

n.b. also works when total number of facets is divisible by the row number

library(ggplot2)

zzz <- data.frame(gp = c("a","b","c","d","e","f"), 
                  c1 = c(1,1,1,1,1,1), 
                  c2 = c(1,1,1,1,1,1))

ggplot(zzz, aes(x = c1, y = c2)) +
  facet_wrap(~ gp, scales = "free", nrow = 3, strip.position = "bottom") +
  geom_point() +
  theme(
    aspect.ratio = 1,
    strip.background = element_blank(),
    strip.placement = "outside"
  )

Created on 2018-05-17 by the reprex package (v0.2.0).

Also, though, with a missing facet that's 2 of 2…

zzz <- data.frame(gp = c("a","b","c","d","e"), 
                  c1 = c(1,1,1,1,1), 
                  c2 = c(1,1,1,1,1))

ggplot(zzz, aes(x = c1, y = c2)) +
  facet_wrap(~ gp, scales = "free", nrow = 3, strip.position = "bottom") +
  geom_point() +
  theme(
    aspect.ratio = 1,
    strip.background = element_blank(),
    strip.placement = "outside"
  )
#> Warning: Suppressing axis rendering when strip.position = 'bottom' and
#> strip.placement == 'outside'

[clauswilke]

I can't say I understand the code in question, but one way or another this line looks suspicious:

ggplot2/R/facet-wrap.r

Line 300 in 4b609fb

any(!vapply(row_axes, is.zero, logical(length(row_axes))))) {

There's a similar line a little further down, though I wasn't able to create a crash at that position:

ggplot2/R/facet-wrap.r

Line 307 in 4b609fb

any(!vapply(col_axes, is.zero, logical(length(col_axes))))) {

The problem with these lines is the last argument to vapply(), e.g. logical(length(row_axes)). When row_axes holds more than one grob, logical(length(row_axes)) will be a vector of bools, but is.zero() will always return only a single bool, hence the error message. I suspect the correct code would be vapply(row_axes, ggplot2:::is.zero, logical(length(1))).

Reprex to show what I mean:

library(grid)
library(ggplot2)

row_axes <- list(zeroGrob(), textGrob("test"))
vapply(row_axes, ggplot2:::is.zero, logical(length(1)))
#> [1]  TRUE FALSE
vapply(row_axes, ggplot2:::is.zero, logical(length(row_axes)))
#> Error in vapply(row_axes, ggplot2:::is.zero, logical(length(row_axes))): values must be length 2,
#>  but FUN(X[[1]]) result is length 1

Created on 2018-05-17 by the reprex package (v0.2.0).

[thomasp85]

I’ll look into it today

[thomasp85]

It seems to be a simple matter of me messing up the the vapply call...

The reason @clauswilke can't provoke an error on the second instance is that it is not possible to have more than a single unfinished row

[lock]

This old issue has been automatically locked. If you believe you have found a related problem, please file a new issue (with reprex) and link to this issue. https://reprex.tidyverse.org/