dask 2021.10.0

NotesParametersReturns
vonmises(self, mu, kappa, size=None, chunks='auto', **kwargs)

This docstring was copied from numpy.random.mtrand.RandomState.vonmises.

Some inconsistencies with the Dask version may exist.

Samples are drawn from a von Mises distribution with specified mode (mu) and dispersion (kappa), on the interval [-pi, pi].

The von Mises distribution (also known as the circular normal distribution) is a continuous probability distribution on the unit circle. It may be thought of as the circular analogue of the normal distribution.

note

New code should use the vonmises method of a default_rng() instance instead; please see the :None:ref:`random-quick-start`.

Notes

The probability density for the von Mises distribution is

$$p(x) = \frac{e^{\kappa cos(x-\mu)}}{2\pi I_0(\kappa)},$$

where $\mu$ is the mode and $\kappa$ the dispersion, and $I_0(\kappa)$ is the modified Bessel function of order 0.

The von Mises is named for Richard Edler von Mises, who was born in Austria-Hungary, in what is now the Ukraine. He fled to the United States in 1939 and became a professor at Harvard. He worked in probability theory, aerodynamics, fluid mechanics, and philosophy of science.

Parameters

mu : float or array_like of floats

Mode ("center") of the distribution.

kappa : float or array_like of floats

Dispersion of the distribution, has to be >=0.

size : int or tuple of ints, optional

Output shape. If the given shape is, e.g., (m, n, k) , then m * n * k samples are drawn. If size is None (default), a single value is returned if mu and kappa are both scalars. Otherwise, np.broadcast(mu, kappa).size samples are drawn.

Returns

out : ndarray or scalar

Drawn samples from the parameterized von Mises distribution.

Draw samples from a von Mises distribution.

See Also

Generator.vonmises

which should be used for new code.

scipy.stats.vonmises

probability density function, distribution, or cumulative density function, etc.

Examples

Draw samples from the distribution:

This example is valid syntax, but we were not able to check execution
>>> mu, kappa = 0.0, 4.0 # mean and dispersion  # doctest: +SKIP
... s = np.random.vonmises(mu, kappa, 1000) # doctest: +SKIP

Display the histogram of the samples, along with the probability density function:

This example is valid syntax, but we were not able to check execution
>>> import matplotlib.pyplot as plt  # doctest: +SKIP
... from scipy.special import i0 # doctest: +SKIP
... plt.hist(s, 50, density=True) # doctest: +SKIP
... x = np.linspace(-np.pi, np.pi, num=51) # doctest: +SKIP
... y = np.exp(kappa*np.cos(x-mu))/(2*np.pi*i0(kappa)) # doctest: +SKIP
... plt.plot(x, y, linewidth=2, color='r') # doctest: +SKIP
... plt.show() # doctest: +SKIP
See :

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