Qfyilyi

I need to find distance in eastward direction from each point to the closest polygon edge:

I can find distance in any direction with:

pointlayer = QgsProject.instance().mapLayersByName('points_inter_squares')[0]

points = [[f.geometry(),f['Ruta_100km']] for f in pointlayer.getFeatures()]



squarelayer = QgsProject.instance().mapLayersByName('squares')[0]

squares = [[f.geometry(),f['Ruta_100km']] for f in squarelayer.getFeatures()]



for point in points:

    print(min([QgsGeometry.distance(point[0],square[0]) for square in squares if point[1]!=square[1]]))



>>12639.380321901293

>>3320.150455611874

>>6650.862023710273

>>2452.079442886869

'Ruta_100km' is the Squares IDs, so I measure distance to all Squares but the one intersecting the Points.

Is there a method where I can specify direction when measuring distance?

A general solution: Provided a grid described by it's origin (x0, y0) and a grid spacing d_grid (100km in your example), the problem reduces to calculate the difference between the test points p = (x, y) y-coordinate and the y-coordinate of the grid line lying next to p, y_square, so the question is, what is y_square:

The following does not need a grid layer, but only the description of the grid as described above:

for p in points:

    # assumption: grid origin (x0, y0), spacing d_grid

    # metric coordinate system

    y = p.geometry().asPoint().y()

    # calculate y-distance to origin

    dy0 = y - y0

    # calculate number of square in which p(x, y) lies (2 in the example)

    square_count = int(dy0 / d_grid) + 1

    # calculate y-coordinate of grid line next to p

    y_square = y0 + d_grid * square_count

    # calculate the desired distance

    dp = y_square - y

    print(dp)