Error when using FFT on data with one point

[Python-simulation]

Activating the FFT transform on data with one point raises the following error:

File ~\anaconda3\lib\site-packages\pyqtgraph\graphicsItems\PlotDataItem.py:1190 in _fourierTransform
uniform = not np.any(np.abs(dx-dx[0]) > (abs(dx[0]) / 1000.))
IndexError: index 0 is out of bounds for axis 0 with size 0

This occurs because dx = np.diff(x) is empty when x is of size 1.

A possible solution is to add the following condition if len(x) == 1: return np.array([0]), abs(y) in the beginning of _fourierTransform in PlotDataItem.py.

• PyQtGraph version: tested on 0.13.3 but will also raise same error in 0.13.7 has the relevant code has not changed.

[j9ac9k]

We probably shouldn't be raising an exception, but I'm struggling to think of what the ideal behavior should be.

>>> np.fft.rfft(np.array([1]))
array([1.+0.j])
>>> np.fft.rfft(np.array([5]))
array([5.+0.j])

I do think the solution you've proposed is probably the best tho.