CODEWITHSUNDEEP
pythonmappingphase
Heißenberg93
Heißenberg93

Reputation: 1919

Get angle into range 0 - 2*pi - python

In my simulation i compute multiple values for a phase, for example

phi = np.linspace(-N,N,1000)

where N can be large.

Is there an easy way to map the values to the intervall [0,2pi) ?

Upvotes: 3

Views: 20696

Answers (3)

Bernardo Costa
Bernardo Costa

Reputation: 509

Another possible way:

First, convert to the [-pi, pi] interval using np.arctan2(np.sin(angle), np.cos(angle)). Then, you still need to transform the negative values. A final function like this would work:

 def convert_angle_to_0_2pi_interval(angle):
    new_angle = np.arctan2(np.sin(angle), np.cos(angle))
    if new_angle < 0:
        new_angle = abs(new_angle) + 2 * (np.pi - abs(new_angle))
    return new_angle

To confirm, run:

angles = [10, 200, 365, -10, -180]
print(np.rad2deg([convert_angle_to_0_2pi_interval(np.deg2rad(a)) for a in angles]))

...which prints: [ 10., 200., 5., 350., 180.]

Upvotes: 1

spyr03
spyr03

Reputation: 882

It sounds like you are looking for np.interp. Scipy offers an interpolate function too.

For a usage example, to map the values of phi (which are between -N and N) to [0, 2π] try

np.interp(phi, (-N, N), (0, 2*np.pi))

To exclude 2π you could either change upper bound so no value maps onto 2π.

np.interp(phi, (-N, N + 1), (0, 2*np.pi))

Or reduce the largest value you include in phi

phi = np.linspace(-N, N, 1000, endpoint=False)

I believe it would be easier to just ask for the values directly.

For example, 1000 points over the range [0, 2π] can be given by

np.linspace(0, 2*np.pi, 1000)

And for the range [0, 2π) which excludes the value 2π

np.linspace(0, 2*np.pi, 1000, endpoint=False)

Upvotes: 2

Cl&#233;ment
Cl&#233;ment

Reputation: 1256

Does that work ?

import numpy as np
import math

N=10
phi = np.linspace(-N,N,1000)

phi = phi%(2*math.pi)

print(phi)

Output 

[2.56637061 2.58639063 ... 3.69679467 3.71681469]

Upvotes: 7

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