I wonder if it is possible to specify the point radius of geom\_points in the same unit as the axes (meters in my example). I have inventory data where the sampling probability of a tree relies to an individual radius.

```
# reading some example data
dat <- read.table(header=TRUE, text="x y radius
0 0  7.5
10 0 5.5
20 0 7
30 0 9")
dat
#>    x y radius
#> 1  0 0    7.5
#> 2 10 0    5.5
#> 3 20 0    7.0
#> 4 30 0    9.0

```

I therefore need to draw the tree specific radius exactly to explain the method visually. I found older questions (like this four year old discussion: [geom\_point control radius exactly rather than scaling it](https://stackoverflow.com/questions/23908147/geom-point-control-radius-exactly-rather-than-scaling-it)) where the same problem was not finally solved. I wondered if there are may more recent approaches. I played around with scale\_radius and scale\_size\_area but did not succeed. This is the code I tryed

```
ggplot(data = dat, aes(x = x, y = y, color = factor(dat$Nutz), size = radius * 2)) + 
geom_point() + scale_radius(name = NULL, range = c(0, 50))

```

This gives what I am looking for using the graphics package

```
plot(dat$x, dat$y, asp = 1, xlim = c(0, 50),ylim = c(0, 50))
symbols(dat$x, dat$y, circles = dat$radius, inches = FALSE, add = TRUE)

```

[![enter image description here](https://i.stack.imgur.com/wzpyn.png)](https://i.stack.imgur.com/wzpyn.png)

Does anyone have a clue? All the best, Kai