Parametrize r_rescale

[KryeKuzhinieri]

We are facing issues to fill the blank space in pie charts using ggplot2_3.5.1 (issue in other versions too).

The following code:

library(ggplot2)

# Create Data
data <- data.frame(
  group=LETTERS[1:5],
  value=c(13,7,9,21,2)
)

# Basic piechart
ggplot(data, aes(x="", y=value, fill=group)) +
  geom_bar(stat="identity", width=1) +
  coord_polar("y", start=0) +
  theme_gray() +
  theme(
    panel.grid.major = element_blank(),
    panel.grid.minor = element_blank(),
    axis.text.x = element_blank(),
  )

Gives the following graph:

The issue seems to arise from the r_rescale function which has the donut = c(0, 0.4) hardcoded. This can be fixed by overriding the function as shown below:

library(scales)
library(ggplot2)

# Create Data
data <- data.frame(
  group=LETTERS[1:5],
  value=c(13,7,9,21,2)
)

custom_r_rescale <- function(x, range, donut = c(0, 0.49)) {
  x <- squish_infinite(x, range)
  rescale(x, donut, range)
}
assignInNamespace("r_rescale", custom_r_rescale, ns="ggplot2", pos="package:ggplot2")


ggplot(data, aes(x="", y=value, fill=group)) +
  geom_bar(stat="identity", width=1) +
  coord_polar("y", start=0) +
  theme_gray() +
  theme(
    panel.grid.major = element_blank(),
    panel.grid.minor = element_blank(),
    axis.text.x = element_blank(),
  )

However, this is a hacky way to solve this issue. It seems that the same issue was reported in a stackoverflow issue as well.

The question I have is if it would be possible to parametrize this parameter or this function?

Thanks a lot!

[teunbrand]

I don't think this will be implemented for coord_polar() as it has been superseded by coord_radial().
The reason there is extra space around the edge of the circular area is because it is a place reserved for axis labels.
For that reason, I wouldn't like (the option) to get rid of this space.

If you insist on ignoring the axis label space, you can override the relevant parameter in the coord like so:

# Add this to plot with `+`
  ggproto(
    NULL, coord_radial("y", start=0, expand = FALSE),
    inner_radius = c(0, 0.5)
  )

[KryeKuzhinieri]

Thanks, your suggestion reaches the same result shown in my code. While it is again a hacky way to solve the problem, it does solve it.

Take care!

[r2evans]

I just visited here jumping from https://stackoverflow.com/a/79461775/3358272 ...

@teunbrand,

The reason there is extra space around the edge of the circular area is because it is a place reserved for axis labels

We can control the presence of axis-labels for non-radial plots directly, such as with scale_x_continuous(name=NULL, breaks=NULL) (other ways, perhaps), is there a reason you're averse to doing this for radial as well? (other than adding coord_radial() with that scale_x can result in an error "EXPR must be a length 1 vector"`.

I apologize if I'm misunderstanding the ability of the ggproto(.) call above.

[teunbrand]

is there a reason you're averse to doing this for radial as well?

No the same breaks = NULL mechanism should work for polar/radial coords as well. If they don't, that is probably a (separate) bug. I can see this happening so I'll reopen #6258.

This particular issue is even when guides(theta = "none"), we need to reserve space for axis placement, because the data transformation cannot depend on the state of the guides. This isn't really a problem for cartesian systems as on the gtable level we adjust the cells, but that doesn't work for the circular 'panel' shapes.