Fast Fourier Transform Bug

[Thomas W]

Right clicking a plot, and going to Plot Options -> Transforms -> Power Spectrum results in a crash, which appears to be from the lack of __future__ division.

pyqtgraph/graphicsItems/PlotDataItem.py
line 683, in _fourierTransform

y = abs(f[1:len(f)/2])
TypeError: slice indices must be integers or None or have an __index__ method

[Bob]

I have found this also. I don't suppose there is a fix coming? Is it possible to disable this menu item?

 

[Kenneth Lyons]

This problem looks like it was fixed a couple years ago [1], though that wouldn't have made it into the most recent release (from about 2015). You could try installing from the latest develop branch: https://github.com/pyqtgraph/pyqtgraph#installation-methods

One way to work around this:

plt = pg.plot([1, 2], [1, 2])
plt.getPlotItem().ctrl.fftCheck.setEnabled(False)

That will disable the checkbox for the FFT operation, selectively disabling that feature.

[1] https://github.com/pyqtgraph/pyqtgraph/commit/12f6bf916fbe4357305522cc361b522e2482e9f5

[Bob]

Thanks, disabling the option is fine since the FFT means nothing for my data. 

[itay peled]

Just change this line to:

y = abs(f[1:len(f)//2])

(using // instead of / to get integer for slice index)