dora/examples/python-dataflow/README.md

# Python Dataflow Example

This examples shows how to create and connect dora nodes in Python.

## Overview

The [`dataflow.yml`](./dataflow.yml) defines a simple dataflow graph with the following three nodes:

- a webcam node, that connects to your webcam and feed the dataflow with webcam frame as jpeg compressed bytearray.
- a window plotting node, that will retrieve the webcam image and plot it.

The same dataflow is implemented for a `dynamic-node` in [`dataflow_dynamic.yml`](./dataflow_dynamic.yml). It contains
the same nodes as the previous dataflow, but the plot node is a dynamic node. See the next section for more
information on how to start such a dataflow.

## Getting started

After installing Rust, `dora-cli` and `Python >3.11`, you will need to **activate** (or create and **activate**) a
[Python virtual environment](https://docs.python.org/3/library/venv.html).
Then, you will need to install the dependencies:

```bash
cd examples/python-dataflow
dora build ./dataflow.yml --uv (or dora build ./dataflow_dynamic.yml --uv)
```

It will install the required dependencies for the Python nodes.

Then you can run the dataflow:

```bash
dora run ./dataflow.yml --uv (or dora start ./dataflow_dynamic.yml --uv)
```

**Note**: if you're running the dynamic dataflow, you will need to start manually the opencv-plot node:

```bash
# activate your virtual environment in another terminal
python opencv-plot --name plot
```