numpy.random.RandomState.poisson

方法

random.RandomState.poisson(lam=1.0, size=None)

从泊松分布中提取样本。

泊松分布是大N的二项分布的极限。

注解

新代码应该使用 poisson A方法 default_rng() 请参阅 快速启动 .

参数

lam浮点数或类似浮点数的数组

间隔的期望值必须大于等于0。期望间隔序列必须可以在请求的大小上广播。

sizeint或int的元组，可选

输出形状。如果给定的形状是，例如， (m, n, k) 然后 m * n * k 取样。如果尺寸是 None （默认），如果 lam 是标量。否则， np.array(lam).size 取样。

返回

outndarray或scalar

从参数化泊松分布中提取样本。

参见

Generator.poisson

应该用于新代码。

笔记

泊松分布

System Message: WARNING/2 (f（k；\lambda）=\frac \lambda^k e^-\lambda k！})

latex exited with error [stdout] This is pdfTeX, Version 3.14159265-2.6-1.40.19 (TeX Live 2019/dev/Debian) (preloaded format=latex) restricted \write18 enabled. entering extended mode (./math.tex LaTeX2e <2018-12-01> (/usr/share/texlive/texmf-dist/tex/latex/base/article.cls Document Class: article 2018/09/03 v1.4i Standard LaTeX document class (/usr/share/texlive/texmf-dist/tex/latex/base/size12.clo)) (/usr/share/texlive/texmf-dist/tex/latex/base/inputenc.sty) (/usr/share/texlive/texmf-dist/tex/latex/amsmath/amsmath.sty For additional information on amsmath, use the `?' option. (/usr/share/texlive/texmf-dist/tex/latex/amsmath/amstext.sty (/usr/share/texlive/texmf-dist/tex/latex/amsmath/amsgen.sty)) (/usr/share/texlive/texmf-dist/tex/latex/amsmath/amsbsy.sty) (/usr/share/texlive/texmf-dist/tex/latex/amsmath/amsopn.sty)) (/usr/share/texlive/texmf-dist/tex/latex/amscls/amsthm.sty) (/usr/share/texlive/texmf-dist/tex/latex/amsfonts/amssymb.sty (/usr/share/texlive/texmf-dist/tex/latex/amsfonts/amsfonts.sty)) (/usr/share/texlive/texmf-dist/tex/latex/anyfontsize/anyfontsize.sty) (/usr/share/texlive/texmf-dist/tex/latex/tools/bm.sty) (./math.aux) (/usr/share/texlive/texmf-dist/tex/latex/amsfonts/umsa.fd) (/usr/share/texlive/texmf-dist/tex/latex/amsfonts/umsb.fd) ! Argument of \split has an extra }. <inserted text> \par l.14 ...lambda）=\frac \lambda^k e^-\lambda k！} \end{split} Runaway argument? f（k；\lambda ）=\frac \lambda ^k e^-\lambda k！ ! Paragraph ended before \split was complete. <to be read again> \par l.14 ...lambda）=\frac \lambda^k e^-\lambda k！} \end{split} ! Missing $ inserted. <inserted text> $ l.14 ...lambda）=\frac \lambda^k e^-\lambda k！} \end{split} ! Missing \endgroup inserted. <inserted text> \endgroup l.14 ...lambda）=\frac \lambda^k e^-\lambda k！} \end{split} ! Missing \endgroup inserted. <inserted text> \endgroup l.14 ...lambda）=\frac \lambda^k e^-\lambda k！} \end{split} ! Display math should end with $$. <to be read again> \par l.14 ...lambda）=\frac \lambda^k e^-\lambda k！} \end{split} ! Extra }, or forgotten \endgroup. <recently read> } l.14 ...lambda）=\frac \lambda^k e^-\lambda k！} \end{split} ! Misplaced \crcr. \endsplit ->\crcr \egroup \egroup \iftagsleft@ \@xp \lendsplit@ \else \@xp \... l.14 ...frac \lambda^k e^-\lambda k！}\end{split} ! Extra }, or forgotten \endgroup. \endsplit ->\crcr \egroup \egroup \iftagsleft@ \@xp \lendsplit@ \else \@xp \... l.14 ...frac \lambda^k e^-\lambda k！}\end{split} ! Extra }, or forgotten \endgroup. \endsplit ->\crcr \egroup \egroup \iftagsleft@ \@xp \lendsplit@ \else \@xp \... l.14 ...frac \lambda^k e^-\lambda k！}\end{split} ! LaTeX Error: \begin{equation*} on input line 13 ended by \end{split}. See the LaTeX manual or LaTeX Companion for explanation. Type H <return> for immediate help. ... l.14 ...frac \lambda^k e^-\lambda k！}\end{split} ! Missing $ inserted. <inserted text> $ l.14 ...frac \lambda^k e^-\lambda k！}\end{split} ! LaTeX Error: \begin{document} ended by \end{equation*}. See the LaTeX manual or LaTeX Companion for explanation. Type H <return> for immediate help. ... l.15 \end{equation*} ! Missing $ inserted. <inserted text> $ l.15 \end{equation*} ! Extra \endgroup. <recently read> \endgroup l.15 \end{equation*} [1] (./math.aux) ) (see the transcript file for additional information) Output written on math.dvi (1 page, 156 bytes). Transcript written on math.log.

对于预期分离的事件 泊松分布 描述的概率 在观察间隔内发生的事件 .

因为输出被限制在C int64类型的范围内，所以当 lam 在最大可表示值的10西格玛范围内。

工具书类

1

“泊松分布”，摘自《数学世界——一个Wolfram网络资源》。http://mathworld.wolfram.com/poissondistribution.html

2

维基百科，“泊松分布”，https://en.wikipedia.org/wiki/poisson_distribution

实例

从分发中抽取样本：

>>> import numpy as np
>>> s = np.random.poisson(5, 10000)

显示样本的柱状图：

>>> import matplotlib.pyplot as plt
>>> count, bins, ignored = plt.hist(s, 14, density=True)
>>> plt.show()

为lambda 100和500分别绘制100个值：

>>> s = np.random.poisson(lam=(100., 500.), size=(100, 2))

numpy.random.RandomState.pareto numpy.random.RandomState.power