# Using the Monitor

![Monitor](images/monitor.png)

The monitor allows visualizing information related to the agents or training
process within a Unity scene.

You can track many different things both related and unrelated to the agents
themselves. By default, the Monitor is only active in the *inference* phase, so
not during training. To change this behavior, you can activate or deactivate it
by calling `SetActive(boolean)`. For example to also show the monitor during
training, you can call it in the `InitializeAcademy()` method of your `Academy`:

```csharp
using MLAgents;

public class YourAcademy : Academy {
    public override void InitializeAcademy()
    {
        Monitor.SetActive(true);
    }
}
```

To add values to monitor, call the `Log` function anywhere in your code:

```csharp
Monitor.Log(key, value, target)
```

* `key` is the name of the information you want to display.
* `value` is the information you want to display. *`value`* can have different
  types:
  * `string` - The Monitor will display the string next to the key. It can be
    useful for displaying error messages.
  * `float` - The Monitor will display a slider. Note that the values must be
    between -1 and 1. If the value is positive, the slider will be green, if the
    value is negative, the slider will be red.
  * `float[]` - The Monitor Log call can take an additional argument called
    `displayType` that can be either `INDEPENDENT` (default) or `PROPORTIONAL`:
    * `INDEPENDENT` is used to display multiple independent floats as a
      histogram. The histogram will be a sequence of vertical sliders.
    * `PROPORTION` is used to see the proportions between numbers. For each
      float in values, a rectangle of width of value divided by the sum of all
      values will be show. It is best for visualizing values that sum to 1.
* `target` is the transform to which you want to attach information. If the
  transform is `null` the information will be attached to the global monitor.
  * **NB:** When adding a target transform that is not the global monitor, make
    sure you have your main camera object tagged as `MainCamera` via the
    inspector. This is needed to properly display the text onto the screen.