I just tried to create a histogram build upon a list of characters like this:

```
histogram [a c a c b c a c c c c c c a c c a c a c a a c c c a a b c b c]
```

But it doesn't show anything. Is it just supposed to handle numbers or am I missing something?

# Best How To :

You didn´t use quotes in your histogram list, but I am assuming that you wanted to plot a list of strings like ["a" "b" "c" ...], right?

As far as I know, it is not possible to use categorical values (like strings) for a histogram in netlogo plots. This is also stated in the netlogo dictionary: histogram [...] Any non-numeric values in the list are ignored. [...]

One way to solve this would be a conversion to a numeric list by just giving every string-character a specific number:

```
let m ["a" "c" "a" "c" "b" "c" "a" "a" "c" "c" "b" "b" "c" "c" "a" "a"]
let n [ ]
foreach m
[
if (? = "a") [set n lput 0 n]
if (? = "b") [set n lput 1 n]
if (? = "c") [set n lput 2 n]
;...
]
histogram n
```