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r ggplot2

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July 23, 2025 Score: 3 Rep: 168,671 Quality: Medium Completeness: 100%

With geomcol(), where there are multiple observations for each x-value:

  • if the y-value is numeric or integer, geomcol() stacks the observations by x (thanks to JonSpring for clarifying this);
  • if the y-value is logical or categorical, it stacks the values by y

Stacking, broken out:

data("mpg", package="ggplot2")
library(ggplot2)
library(dplyr) # just for demonstration
ggplot(mpg, aes(x = hwy, y = cyl)) +
  geomcol(color = "white")

ggplot grob with geom</em></i>col, changing color to show it is stacked

This looks like summing in a sense (when color/fill is not changed), shown here via explicit aggregation:

summarize(mpg, .by = hwy, cyl = sum(cyl)) |>
  ggplot(aes(x = hwy, y = cyl)) +
  geomcol()

original ggplot created by explicitly summing the cyl value for each unique hwy value

To work around the fact that cyl is numeric or integer, we can force it to be a categorical value with factor(.):

ggplot(mpg, aes(x = hwy, y = factor(cyl))) +
  geomcol()

ggplot of mpg data with cyl as a factor

The "striations" in that shows that it is stacking all of the hwy values in an additive sense (not summing):

slicehead(mpg, by = cyl, n = 3)

# A tibble: 12 × 11


   manufacturer model              displ  year   cyl trans      drv     cty   hwy fl    class     


                                           


 1 audi         a4                   1.8  1999     4 auto(l5)   f        18    29 p     compact   


 2 audi         a4                   1.8  1999     4 manual(m5) f        21    29 p     compact   


 3 audi         a4                   2    2008     4 manual(m6) f        20    31 p     compact   


 4 audi         a4                   2.8  1999     6 auto(l5)   f        16    26 p     compact   


 5 audi         a4                   2.8  1999     6 manual(m5) f        18    26 p     compact   


 6 audi         a4                   3.1  2008     6 auto(av)   f        18    27 p     compact   


 7 audi         a6 quattro           4.2  2008     8 auto(s6)   4        16    23 p     midsize   


 8 chevrolet    c1500 suburban 2wd   5.3  2008     8 auto(l4)   r        14    20 r     suv       


 9 chevrolet    c1500 suburban 2wd   5.3  2008     8 auto(l4)   r        11    15 e     suv       


10 volkswagen   jetta                2.5  2008     5 auto(s6)   f        21    29 r     compact   


11 volkswagen   jetta                2.5  2008     5 manual(m5) f        21    29 r     compact   


12 volkswagen   new beetle           2.5  2008     5 manual(m5) f        20    28 r     subcompact

slicehead(mpg, by = cyl, n = 3) |>
  ggplot(aes(x = hwy, y = factor(cyl))) +
  geom_col(color = "black", fill = "gray")

ggplot of mpg, first three rows for each distinct value of cyl, showing stacked nature of the hwy values