泊松密度曲线，直方图和阴影面积与ggplot2？ [英] Poisson density curve, histogram and shaded area with ggplot2?

问题描述

如何制作：
a）密度曲线和直方图显示lambda = 2.5的泊松分布;和
b）一个密度曲线，阴影面积显示P（X> = 4，lambda = 2.5）b
$ b

x轴应该是0到10

解决方案

泊松分布是一个离散概率分布（函数仅在整数值处定义）。所以不是一条线，它最好用整数值的点表示。为了给函数下的特定范围着色，可以使用 geom =area和 xlim = c（min（range），max（range） / code>：

  ggplot（data.frame（x = 0:10），aes（x））+ 
 stat_function（geom =point，n = 11，fun = dpois，args = list（lambda = 2.5））+ 
 stat_function（geom =area，aes（x），n = 7 ，fun = dpois，args = list（lambda = 2.5），xlim = c（4,10），fill =lightblue，alpha = 0.5）+ 
 theme_bw（）+ 
 scale_x_continuous（breaks = 0:10）
  

如果 stat_function 中的 n 参数与整数值的数目不匹配在一定范围内，情节会显得怪异。

How to make: a) a density curve and histogram displaying a poisson distribution with lambda = 2.5; and b) a density curve with shaded area showing P(X >= 4 with lambda = 2.5)

the x axis should be 0 to 10

解决方案

Poisson distribution is a discrete probability distribution (function is defined only at integer values). So instead of a line it is better represented with points at integer values. To color a specific range under a function one can use geom = "area" and xlim = c(min(range), max(range):

ggplot(data.frame(x = 0:10), aes(x)) +
  stat_function(geom = "point", n = 11, fun = dpois, args = list(lambda = 2.5)) +
  stat_function(geom = "area", aes(x), n = 7, fun = dpois, args = list(lambda = 2.5), xlim = c(4,10), fill = "lightblue", alpha = 0.5)+
  theme_bw()+
  scale_x_continuous(breaks = 0:10)

If the n argument in stat_function does not match the number of integer values over a range the plot is going to look funky.

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