How to use earlier declared variables within aes in ggplot with special operators (..count.., etc.)

Question

Let's say I want to plot histogram with the following formula (I know it's not the best but it will illustrate the problem): ``` set.seed(1) dframe <- data.frame(val=rnorm(50)) p <- ggplot(dframe, aes(x=val, y=..count..)) p + geom_bar() ``` It works just fine. However let's say that we want for some reason frequencies divided by an earler defined number. My shot would be: ``` k <- 5 p <- ggplot(dframe, aes(x=val, y=..count../k)) p + geom_bar() ``` However I get this annoying error: ``` Error in eval(expr, envir, enclos) : object 'k' not found ``` Does there exist a way for using both `..count..`-like variables with some predefined ones?

Accepted Answer

It seems that there is some bug with `ggplot()` function when you use some `stat` for plotting (for example `y=..count..`). Function `ggplot()` has already `environment` variable and so it can use variable defined outside this function.

For example this will work because `k` is used only to change `x` variable:

```
k<-5
ggplot(dframe,aes(val/k,y=..count..))+geom_bar()
```

This will give an error because `k` is used to change `y` that is calculated with stat `y=..count..`

```
k<-5
ggplot(dframe,aes(val,y=..count../k))+geom_bar()
Error in eval(expr, envir, enclos) : object 'k' not found
```

To solve this problem you can kefine `k` inside the `aes()`.

```
k <- 5
ggplot(dframe,aes(val,k=k,y=..count../k))+geom_bar()
```

How to use earlier declared variables within aes in ggplot with special operators (..count.., etc.)

Solution

Problem