Live Plotting of Multiple EMG Channels
===========================================

This example demonstrates how to visualize live EMG data from multiple channels using the RHX device and Matplotlib’s animation features.

.. image:: live_plotting_demo.gif
    :alt: Live plotting of EMG channels with Intan
    :width: 600
    :align: center

**Requirements:**

- Intan RHX Controller with TCP servers enabled (Remote Control)
- `matplotlib` (with Qt5Agg backend; `pip install matplotlib pyqt5`)
- A running RHX TCP server

You’ll see how to:
- Connect to the RHX device over TCP
- Stream EMG data from selected channels in real time
- Display a scrolling plot for each channel in a shared window

----

**Example code:**

.. code-block:: python

    """
    Example: Live plotting of multiple EMG channels from an Intan RHX device.
    Streams channels 10-15 and displays them in real time.
    """

    import time
    import numpy as np
    import matplotlib
    matplotlib.use("Qt5Agg")  # Use fast, responsive backend
    import matplotlib.pyplot as plt
    import matplotlib.animation as animation
    from intan.rhx_interface import IntanRHXDevice

    # === Configuration ===
    CHANNELS = [10, 11, 12, 13, 14, 15]
    SAMPLING_RATE = 4000
    WINDOW_SEC = 1.0
    PLOT_UPDATE_HZ = 5  # Refresh every 200 ms

    SAMPLES_PER_WINDOW = int(SAMPLING_RATE * WINDOW_SEC)
    PLOT_INTERVAL_SEC = 1 / PLOT_UPDATE_HZ
    x_data = np.linspace(-WINDOW_SEC, 0, SAMPLES_PER_WINDOW)

    # === Initialize RHX Device ===
    device = IntanRHXDevice()
    if not device.connected:
        raise RuntimeError("Could not connect to RHX TCP server. Make sure it's running.")
    device.configure(channels=CHANNELS, blocks_per_write=1, enable_wide=True)

    # === Setup Plotting ===
    fig, axs = plt.subplots(len(CHANNELS), 1, figsize=(10, 6), sharex=True)
    axs = np.atleast_1d(axs)
    lines = {}
    buffers = {}

    for ax, ch in zip(axs, CHANNELS):
        ax.set_ylabel("µV")
        ax.set_ylim(-200, 200)
        ax.grid(False)
        ax.set_title("")
        ax.legend().set_visible(False)

        line, = ax.plot(x_data, np.zeros(SAMPLES_PER_WINDOW), label=f"A-{ch:03d}", color="cyan", linewidth=1)
        lines[ch] = line
        buffers[ch] = np.zeros(SAMPLES_PER_WINDOW)

    axs[-1].set_xlabel("Time (s)")
    fig.suptitle("Live EMG: " + ", ".join([f"A-{ch:03d}" for ch in CHANNELS]))
    fig.tight_layout(rect=[0, 0, 1, 0.96])

    # === Update Function ===
    def update_plot(_):
        n_frames = int(SAMPLING_RATE * PLOT_INTERVAL_SEC)
        start_time = time.time()
        try:
            _, channel_array = device.stream(n_frames=n_frames)
        except Exception as e:
            print(f"[Stream Error] {e}")
            return lines.values()

        elapsed = time.time() - start_time
        for i, ch in enumerate(CHANNELS):
            new_data = channel_array[i]
            num_new = min(len(new_data), SAMPLES_PER_WINDOW)
            buffers[ch] = np.roll(buffers[ch], -num_new)
            buffers[ch][-num_new:] = new_data[-num_new:]
            lines[ch].set_ydata(buffers[ch])

        rate = channel_array.shape[1] / elapsed if elapsed > 0 else 0
        print(f"{channel_array.shape[1]} samples/ch in {elapsed:.3f} s → {rate:.1f} Hz")
        return lines.values()

    # === Animation Loop ===
    ani = animation.FuncAnimation(
        fig, update_plot,
        interval=int(PLOT_INTERVAL_SEC * 1000),
        blit=True
    )

    try:
        print(f"Streaming Channels: {', '.join([f'A-{ch:03d}' for ch in CHANNELS])}")
        plt.show()
    except KeyboardInterrupt:
        print("Interrupted.")
    finally:
        device.close()
        print("RHX device connection closed.")

----

**Expected outcome:**

- Real-time, continuously updating plots for each selected channel
- All channels appear in a single window stacked vertically
- Streaming rate is printed in the terminal

**Tips:**
- You can adjust the `CHANNELS` list to select different channels.
- For a more responsive UI or to support additional features, see the PyQtGraph-based example in the next tutorial.

----

**Troubleshooting:**
- Make sure the Intan RHX TCP server is running and channels are enabled for streaming.
- If you see “Could not connect to RHX TCP server”, open the Remote Control GUI in RHX and enable both servers.
- Install PyQt5 if you see backend errors: `pip install pyqt5`