Ganglion using Matplotlib to graph, produces weird results ?

bruvbruv Houston
edited July 2021 in Software

I just graphed the time series data of a Ganglion board EEG recording from channel 1 and got the following plot (EEG vs time). Has anyone else gotten this before? What am I doing wrong as this clearly isn't a waveform.

Comments

  • Should you have both an x vector and a y vector in your plot() statement?

  • bruvbruv Houston

    I tried and I still got the same graph.
    The lack of an x vector isn't the problem since plt.plot() just uses the indices of the argument as the x variable as default if only one argument is given.

  • wjcroftwjcroft Mount Shasta, CA

    Bruv, hi.

    Bill, thanks.

    You can access the Ganglion board directly in real-time from Matlab, using Brainflow,

    https://brainflow.readthedocs.io/en/stable/Examples.html#matlab

    William

  • bruvbruv Houston

    Is there a way to do the same thing in python?

  • wjcroftwjcroft Mount Shasta, CA

    Read through the docs, multiple languages are supported,

    https://brainflow.readthedocs.io/en/stable/Examples.html#python

  • wjcroftwjcroft Mount Shasta, CA

    There is a Slack group for questions, sign up via link on this page,

    https://brainflow.org/

  • edited July 2021

    The graph appears to be a line graph composed of 2 components. One, the bottom of the vertical lines, is a somewhat sinusoidal graph, and might be data. The other is a linearly increasing function which might be time points. Why your plot could be drawing nearly vertical lines between 2 perhaps alternating sets of data is the question.

  • bruvbruv Houston

    I agree Bill. It's interesting that the baseline from which the sinusoid returns to each cycle is linearly increasing. I wonder if this is a result of a recording artifact.

  • If the data was not just voltage readings but was a time measure (as in the time() computer function) interleaving somehow with a microvolts type EEG voltage reading, it might look like this.

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