# Heatmap Chart

The data format for heatmap chart **per-series** is similar to cartesian charts. But instead of y values they are heat values. The series names will be the y values.

```ruby
{
  <x value> => <heat value>,
  <x value> => <heat value>,
  ...
}
```

or this:

```ruby
[
  [<x value>, <heat value>],
  [<x value>, <heat value>],
  ...
]
```