Color points by their occurrence count in ggplot2 geom_count

Question

I want to color the points drawn by ggplot2's geom_count based on their count.

This is what I have so far:

ggplot(test3, aes(eleStart, eleLength)) +  geom_count(aes(alpha=0.25, color= ..prop..)) +
  scale_y_continuous(breaks=seq(0,130,5)) +
  scale_x_continuous(breaks=seq(0,114)) +
  theme(panel.grid.minor = element_blank())

Now I basically just want to exchange the color=..prop.. with the actual count calculated by geom_count, not their proportion.

test3 dataframe looks like:

# A tibble: 294 x 2
# Groups:   X1 [56]
eleStart eleLength
<int>     <int>
1        0         3
2        0         6
3        0         7
4        0         9
5        0        11
6        0        23
7        0        25
8        0        26
9        0        26
10       0        26
# ... with 284 more rows

Answer 1

You can color points by their occurance with color = ..n.. in aes. See the follow example:

ggplot(mtcars, aes(cyl, carb)) + geom_count(aes(color = ..n..))

To know all the computed variables that can be accessed with ..x.. syntax, you can check the manual of a geom_* function for "Computed variables". For geom_count, it looks like:

Computed variables

n number of observations at position

prop percent of points in that panel at that position

---

If you want to "combine the 2 legends into one legend with colorized points", try the following:

ggplot(mtcars, aes(cyl, carb)) +
    geom_count(aes(color = ..n.., size = ..n..)) +
    guides(color = 'legend')

Color was displayed as colorbar by default. Here, guides(color = 'legend') tells ggplot to dispaly it as legend instead of a seperate colorbar.

Answer 2

If you examine the help file for the geom_count function: help(geom_count), you will see a list of its Computed variables.

Computed variables

n

number of observations at position

prop

percent of points in that panel at that position

So you can use geom_count(aes(alpha=0.25, color= ..n..)) to color by the number of observations at a position and geom_count(aes(alpha=0.25, color= ..prop..)) to color by the percent of points at that position.