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Improve description of shapes 

Fixes #244
This commit is contained in:
hadley 2016-08-12 12:41:49 -05:00
parent 2d0771ccd9
commit 19ea5ad5c8
1 changed files with 7 additions and 5 deletions
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visualize.Rmd
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@ -163,15 +163,15 @@ ggplot(data = mpg) +
Here, the color doesn't convey information about a variable, but only changes the appearance of the plot. To set an aesthetic manually, set the aesthetic by name as an argument of your geom function. You'll need to pick a value that makes sense for that aesthetic:
* the name of a color as a character string.
* the size of a point in mm.
* the shape as a point as a number, as shown below.
* The name of a color as a character string.
* The size of a point in mm.
* The shape of a point as a number, as shown below.
R has a set of 24 built-in shapes, identified by numbers:
R has a set of 25 built-in shapes, identified by numbers:
```{r echo = FALSE, out.width = "75%", fig.asp = 1/3}
shapes <- tibble(
shape = c(0:19, 22, 21, 24, 23, 20),
shape = c(0, 1, 2, 5, 3, 4, 6:19, 22, 21, 24, 23, 20),
x = (0:24 %/% 5) / 2,
y = (-(0:24 %% 5)) / 4
)
@ -186,6 +186,8 @@ ggplot(shapes, aes(x, y)) +
theme(aspect.ratio = 1/2.75)
```
Note that there are some seeming duplicates: 0, 15, and 22 are all squares. The difference comes from the interaction of the `colour` and `fill` aesthetics. The hollow shapes (0--14) have a border determined by `colour`; the solid shapes (15--18) are filled with `colour`; the filled shapes (21--24) have a border of `colour` and are filled with `fill`.
### Exercises
1. What's gone wrong with this code? Why are the points not blue?