Function _shift_resample

phi/field/_resample.py:341–364

(self: Field, resolution: Shape, bounds: Box, threshold=1e-5, max_padding=20)

def _shift_resample(self: Field, resolution: Shape, bounds: Box, threshold=1e-5, max_padding=20):
    assert math.all_available(bounds.lower, bounds.upper), "Shift resampling requires 'bounds' to be available."
    lower = math.to_int32(math.ceil(math.maximum(0, self.bounds.lower - bounds.lower) / self.dx - threshold))
    upper = math.to_int32(math.ceil(math.maximum(0, bounds.upper - self.bounds.upper) / self.dx - threshold))
    if math.close(*math.unstack(lower, batch)) and math.close(*math.unstack(upper, batch)):  # incompatible resolutions
        lower = math.unstack(lower, batch)[0]
        upper = math.unstack(upper, batch)[0]
    else:
        return NotImplemented
    total_padding = int(math.sum(lower) + math.sum(upper))
    if total_padding > max_padding and self.extrapolation.native_grid_sample_mode:
        return NotImplemented
    elif total_padding > 0:
        from phi.field import pad
        padded = pad(self, {dim: (int(lower[i]), int(upper[i])) for i, dim in enumerate(self.shape.spatial.names)})
        grid_box, grid_resolution, grid_values = padded.bounds, padded.resolution, padded.values
    else:
        grid_box, grid_resolution, grid_values = self.bounds, self.resolution, self.values
    origin_in_local = grid_box.global_to_local(bounds.lower) * grid_resolution
    if batch(origin_in_local):
        math.assert_close(*math.unstack(origin_in_local, batch), msg=f"sample_subgrid requires equal start but got varying values along batch dim {batch(origin_in_local)}")
        origin_in_local = math.unstack(origin_in_local, batch)[0]
    data = math.sample_subgrid(grid_values, origin_in_local, resolution)
    return data


def centroid_to_faces(u: Field, boundary: Extrapolation, order=2, upwind: Field = None, ignore_skew=False, gradient: Field = None):