# `compare.confusion`

The function [`compare.confusion`](#digger.compare.confusion) compares the observed extent of landslide impact with a simulated extent. It classifies each location within the region of interest into the four elements of the [binary classification confusion matrix](https://en.wikipedia.org/wiki/Confusion_matrix):

:::{list-table} Elements of the binary classification confusion matrix
:widths: 15 30
:header-rows: 1

*   - Name
    - Description
*   - True Positive
    - Observed and predicted as true
*   - False Positive
    - Observed as false but predicted as true
*   - True Negative
    - Observed and predicted as false
*   - False Negative
    - Observed as true but predicted as false
:::

An example of using this functionality is provided in the file `digger/examples/post-run/synthetic/setpostprocess.py`.
```{literalinclude} ../../../../../examples/post-run/synthetic/setpostprocess.py
:language: python
```

:::{attention}
This code snippet is not fully self-sufficient. This snippet relies on simulation output files. To reproduce the example, execute the file `digger/examples/post-run/synthetic/setpostprocess.py` from within the directory in which it is located. **Before** the script is executed either the example simulation must be run or the file `digger/data/synthetic_output.zip` must be unzipped and the resulting directory (`_output`) must be placed within `digger/examples/post-run/synthetic/`.
:::

This code generates a diagnostic figure that visualizes the confusion matrix.

```{figure} ../../../../_static/from_examples/confusion.png
:alt: Example digger.calculate confusion summary figure.

An example of the diagnostic output provided by digger.calculate.confusion.
```

It also generates a yaml file containing all of the calculated metrics. See the [function API](#digger.compare.confusion) for an explanation of each metric.

```{literalinclude} ../../../../_static/from_examples/confusion_metrics.yaml
:language: yaml
```