How to find the gradient of grid-less data in python? - python

I have a pandas data frame containing location data (x_m and y_m) and another variable represented by the color bar in the figure.
Sample figure showing the data points and a possible gradient arrow
How can I obtain the average gradient of all of the data points in my data set? I drew one of the possible solutions showing the gradient vector.
Thank you!
EDIT:
I ended up using scipy.interpolate.griddata, similar to what was done here: https://earthscience.stackexchange.com/questions/12057/how-to-interpolate-scattered-data-to-a-regular-grid-in-python

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