I have been wondering how one could generate an alluvial plot using a data frame in R (e.g. utilizing `ggalluvial` package)

I have a data frame like following

```
   GENE UNTREATED TREATED
1    G1      FOUR    FOUR
2    G2      FOUR    FOUR
3    G3      FOUR    FOUR
4    G4      FOUR   THREE
5    G5     THREE    NONE
6    G6     THREE    NONE
7    G7       TWO   THREE
8    G8       TWO     ONE
9    G9       ONE     ONE
10  G10       TWO     ONE

```

I would like to generate an alluvial plot with this data. For example, 2 bars in the plot will be UNTREATED and TREATED and connections will be based on the proportions of how genes changing their values before and after treatment. It should definitely possible to do this and I didn't seem to get the grasp of alluvial plot concept. Any help would be highly appreciated.

EDIT: Here is a sample sketch I made how the plot would look like

[![enter image description here](https://i.stack.imgur.com/egW5b.jpg)](https://i.stack.imgur.com/egW5b.jpg)

Thank you.