Draw samples from a Poisson distribution.
The Poisson distribution is the limit of the Binomial
distribution for large N.
Parameters : | lam : float
Expectation of interval, should 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.
|
Notes
The Poisson distribution
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For events with an expected separation
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the Poisson
distribution
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describes the probability of
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events occurring within the observed interval
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.
Because the output is limited to the range of the C long type, a
ValueError is raised when lam is within 10 sigma of the maximum
representable value.
References
Examples
Draw samples from the distribution:
>>> import numpy as np
>>> s = np.random.poisson(5, 10000)
Display histogram of the sample:
>>> import matplotlib.pyplot as plt
>>> count, bins, ignored = plt.hist(s, 14, normed=True)
>>> plt.show()
(Source code, png, pdf)