nlcpy.random.Generator.poisson¶
-
Generator.
poisson
(self, lam=1.0, size=None)¶ Draws samples from a Poisson distribution.
The Poisson distribution is the limit of the binomial distribution for large N.
- Parameters
- lamfloat
Expectation of interval, must be >= 0. A sequence of expectation intervals must be broadcastable over the requested size.
- sizeint or tuple of ints, optional
Output shape. If the given shape is, e.g.,
(m, n, k)
, thenm * n * k
samples are drawn.
- Returns
- outndarray
Drawn samples from the parameterized Poisson distribution.
Note
The Poisson distribution
\[f(k; \lambda)=\frac{\lambda^k e^{-\lambda}}{k!}\]For events with an expected separation \(\lambda\) the Poisson distribution \(f(k; \lambda)\) describes the probability of \(k\) events occurring within the observed interval \(\lambda\).
Because the output is limited to the range of the C int64 type, a ValueError is raised when lam is within 10 sigma of the maximum representable value.
Restriction
If lam is neither a scalar nor None : NotImplementedError occurs.
Examples
Draw samples from the distribution:
>>> import nlcpy as vp >>> rng = vp.random.default_rng() >>> s = rng.poisson(5, 10000)
Display histogram of the sample:
>>> import matplotlib.pyplot as plt >>> count, bins, ignored = plt.hist(s.get(), 14, density=True) >>> plt.show()