Source code for photutils.utils.footprints
# Licensed under a 3-clause BSD style license - see LICENSE.rst
"""
This module provides tools for generating footprints.
"""
import numpy as np
__all__ = ['circular_footprint']
[docs]
def circular_footprint(radius, dtype=int):
"""
Create a circular footprint.
A pixel is considered to be entirely in or out of the footprint
depending on whether its center is in or out of the footprint.
The size of the output array is the minimal bounding box for the
footprint.
Parameters
----------
radius : int
The radius of the circular footprint.
dtype : data-type, optional
The data type of the output `~numpy.ndarray`.
Returns
-------
footprint : `~numpy.ndarray`
A footprint where array elements are 1 within the footprint and
0 otherwise.
Examples
--------
>>> from photutils.utils import circular_footprint
>>> circular_footprint(2)
array([[0, 0, 1, 0, 0],
[0, 1, 1, 1, 0],
[1, 1, 1, 1, 1],
[0, 1, 1, 1, 0],
[0, 0, 1, 0, 0]])
"""
if ~np.isfinite(radius) or radius <= 0 or int(radius) != radius:
raise ValueError('radius must be a positive, finite integer greater '
'than 0')
x = np.arange(-radius, radius + 1)
xx, yy = np.meshgrid(x, x)
return np.array((xx**2 + yy**2) <= radius**2, dtype=dtype)