ggplot2 return values

Question

The documentation for ggplot2's stat_bin function states that it returns a new data frame with additional columns. How does one actually get access to this data frame?

Is it possible?

simple <- data.frame(x = rep(1:10, each = 2))
tmp <- stat_bin(data=simple, binwidth=0.1, aes(x))

I have figured out that tmp is an environment, and ls(tmp) will show what objects are in the environment, but after exploring each of these objects, I'm not seeing anything like what is described as a return value.

Answer 1

NOTE: With the current (as of 2022-05-24) version of ggplot2 (3.3.6), the approach described below no longer works. In place of print(tmp) , you should now use ggplot_build(tmp), as noted in @showteth's now-accepted answer.

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As Luciano Selzer mentions, the calculations that produce the table shown below aren't performed until print time. (A look at ggplot2:::print.ggplot() will show that, in its final line, it returns the table invisibly, so it can be captured by assignment for further examination.)

tmp <- ggplot(data=simple) + stat_bin(aes(x), binwidth=0.1)
x <- print(tmp)
head(x[["data"]][[1]])
#   y count    x ndensity ncount density PANEL group ymin ymax xmin xmax
# 1 0     0 0.95        0      0       0     1     1    0    0  0.9  1.0
# 2 2     2 1.05        1      1       1     1     1    0    2  1.0  1.1
# 3 0     0 1.15        0      0       0     1     1    0    0  1.1  1.2
# 4 0     0 1.25        0      0       0     1     1    0    0  1.2  1.3
# 5 0     0 1.35        0      0       0     1     1    0    0  1.3  1.4
# 6 0     0 1.45        0      0       0     1     1    0    0  1.4  1.5

Answer 2

In ggplot2 (3.3.5), I can not get access to the returned data frame with ggplot2:::print.ggplot(), but I get success with ggplot_build:

simple <- data.frame(x = rep(1:10, each = 2))
tmp <- ggplot(data=simple) + stat_bin(aes(x), binwidth=0.1)
# with ggplot_build
x <- ggplot_build(tmp)
head(x[["data"]][[1]])
#   y count   x xmin xmax density ncount ndensity flipped_aes PANEL group ymin ymax colour   fill size linetype alpha
# 1 2     2 1.0 0.95 1.05       1      1        1       FALSE     1    -1    0    2     NA grey35  0.5        1    NA
# 2 0     0 1.1 1.05 1.15       0      0        0       FALSE     1    -1    0    0     NA grey35  0.5        1    NA
# 3 0     0 1.2 1.15 1.25       0      0        0       FALSE     1    -1    0    0     NA grey35  0.5        1    NA
# 4 0     0 1.3 1.25 1.35       0      0        0       FALSE     1    -1    0    0     NA grey35  0.5        1    NA
# 5 0     0 1.4 1.35 1.45       0      0        0       FALSE     1    -1    0    0     NA grey35  0.5        1    NA
# 6 0     0 1.5 1.45 1.55       0      0        0       FALSE     1    -1    0    0     NA grey35  0.5        1    NA