How to plot 'nan' values for coordinates in shape.stim()

Coding
#1

Hi,

I’m inputting coordinates into my ShapeStim function using the vertices parameter. But my coordinates contain ‘nan’ values which I want to plot so I can see the missing section. But I get the following error:

OSError: exception: access violation reading 0xFFFFFFFFFFFFFFFF

So I was wondering how I can get psychopy to read the ‘nan’ value in my array of coordinates.

my coordinates look like this:

> my_coordinates = np.array([[ 0.04283395,-0.71760799],
>  [-0.02222347,-0.71235765],
>  [-0.08029895 ,-0.69315558],
> [nan, nan], 
> etc..
> ]])

I also get related error:

NameError: name ‘nan’ is not defined

Any help would be appreciated, thanks !

#2

Please could you clarify what you want to happen?

The easiest option might be to replace nan with 0 which would highlight the missing coordinates.

#3

Hi @wakecarter ,

I want to plot those nan values so that the image is drawn with those missing coordinates, e.g. if my original coordinates is length 64, then say 4 of those are nan values and it draws the image with those 4 coordinates missing from the image, so structural integrity of image is retained but those 4 coordinates don’t show up when I draw them on my window. I tried to input 0, but it makes the coordinate 0 so shape is distorted-which I don’t want. I’m plotting polygons with these coordinates

I can get the correct plot using matplotlib, which automatically (?) seems to plot the nan values, but I dont know how psychopy or rather shape.Stim can do this?

#4

In that case what you need to do is strip out the nan values before plotting it.

You could cycle through the list and copy valid values to a second list which you plot.

#5

Hi @wakecarter

Thanks for the suggestion,

I’ve tried it but it doesn’t seem to work, since those points just revert to 0 since I’m looping through an empty numpy array and keeping the same (64,2) dimensions. Is there a way I can adjust the lineColor then in the ShapeStim() parameter? so that only those missing/ nan coordinates become invisible?

#6

I made a mistake in the original ShapeStim() argument. I forgot to set closeShape = False. It works now with plotting the np.nan values , Thanks !

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