cf.Data.arctan2¶

classmethod
Data.
arctan2
(x1, x2)[source]¶ Elementwise arc tangent of
x1/x2
with correct quadrant.The quadrant (i.e. branch) is chosen so that
arctan2(y, x)
is the signed angle in radians between the ray ending at the origin and passing through the point(1, 0)
, and the ray ending at the origin and passing through the point(x, y)
. (Note the role reversal: the “ycoordinate” is the first function parameter, the “xcoordinate” is the second.) By IEEE convention, this function is defined forx = +/0
and for either or both ofy = +/inf
andx = +/inf
(see Notes for specific values).arctan2
is identical to theatan2
function of the underlying C library. The following special values are defined in the C standard:x1
x2
arctan2(x1, x2)
+/ 0
+0
+/ 0
+/ 0
0
+/ pi
> 0
+/inf
+0 / +pi
< 0
+/inf
0 / pi
+/inf
+inf
+/ (pi/4)
+/inf
inf
+/ (3*pi/4)
Note that
+0
and0
are distinct floating point numbers, as are+inf
andinf
.New in version 3.16.0.
 Parameters
 x1: array_like
Y coordinates.
 x2: array_like
X coordinates. x1 and x2 must be broadcastable to a common shape (which becomes the shape of the output).
 Returns
Data
Array of angles in radians, in the range
(pi, pi]
.
Examples
>>> import numpy as np >>> x = cf.Data([1, +1, +1, 1]) >>> y = cf.Data([1, 1, +1, +1]) >>> print((cf.Data.arctan2(y, x) * 180 / np.pi).array) [135.0 45.0 45.0 135.0] >>> x[1] = cf.masked >>> y[1] = cf.masked >>> print((cf.Data.arctan2(y, x) * 180 / np.pi).array) [135.0  45.0 135.0]
>>> print(cf.Data.arctan2([0, 0, np.inf], [+0., 0., np.inf]).array) [0.0 3.141592653589793 0.7853981633974483]
>>> print((cf.Data.arctan2([1, 1], [0, 0]) * 180 / np.pi).array) [90.0 90.0]