Steve Steve - 1 year ago 122
Python Question

Python/Psychopy: checking if a point is within a circle

I want to know the most efficient way to check if a given point (an eye coordinate) is within a specific region (in this case a circle).


win = visual.Window([600,600], allowGUI=False)

coordinate = [50,70] #example x and y coordinates

shape = visual.Circle(win, radius=120, units='pix') #shape to check if coordinates are within it

if coordinate in shape:
print "inside"
print "outside"

>>TypeError: argument of type 'Circle' is not iterable

My x and y coordinates correspond to one point on the window, I need to check if this point falls within the circle whose radius is 120 pixels.


Answer Source

PsychoPy's ShapeStim classes have a .contains() method, as per the API:

So your code could simply be:

if shape.contains(coordinate):
    print 'inside'
    print 'outside'

Using this method has the advantage that it is a general solution (taking into account the shape of the stimulus vertices) and is not just a check on the pythagorean distance from the stimulus centre (which is a special case for circles only).

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