How to set a plot widget to Power Spectrum mode?

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I have data being plotted and I need to display its Fourier transform in real time. Right clicking on the plot and going through the Plot Options menu lets me select Power Spectrum mode, but is there any way to have this mode be active when the plot widget is created in the first place? I need the Fourier transform to be displayed without having to go through the clickable menus. Thanks for your help.