updated alpha.py

alpha.py

@@ -0,0 +1,51 @@
+import numpy as np
+import astropy.units as u
+
+
+# TODO: make sure these have up/solar north as the reference of 0 degrees
+
+
+def radial90(shape):
+    '''
+    assumes solar north is to the left - useful for STEREO
+    creates radial polarization map
+    '''
+    x_size, y_size = shape
+    x = np.arange(-x_size // 2, x_size // 2)
+    y = np.arange(-y_size // 2, y_size // 2)
+    xx, yy = np.meshgrid(x, y)
+    return np.fliplr(np.rot90(np.arctan2(yy, xx), k=1))*u.radian
+
+
+def radial_west(shape):
+    '''
+    assumes solar north is up
+    creates radial polarization map
+    '''
+    x_size, y_size = shape
+    x = np.arange(-x_size // 2, x_size // 2)
+    y = np.arange(-y_size // 2, y_size // 2)
+    xx, yy = np.meshgrid(x, y)
+    return np.flipud(np.fliplr(np.arctan2(yy, xx) + np.pi))*u.radian
+
+def radial_north(shape):
+    '''
+    assumes solar north is up
+    creates radial polarization map
+    '''
+    x_size, y_size = shape
+    x = np.arange(-x_size // 2, x_size // 2)
+    y = np.arange(-y_size // 2, y_size // 2)
+    xx, yy = np.meshgrid(x, y)
+    # return np.fliplr(np.arctan2(yy, xx))*u.radian
+    return np.flipud(np.rot90(np.fliplr(np.arctan2(yy, xx) + np.pi), k=1))* u.radian
+#
+
+def zeros(shape):
+    return np.zeros(shape)
+
+
+ALPHA_FUNCTIONS = {'radial_north': radial_north,
+                   'radial_west': radial_west,
+                   'radial90': radial90,
+                   'zeros': zeros}