“密度"直方图上的曲线叠加，其中纵轴是频率(又名计数)还是相对频率? [英] "Density" curve overlay on histogram where vertical axis is frequency (aka count) or relative frequency?

问题描述

当纵轴是频率或相对频率时，有没有一种方法可以叠加类似于密度曲线的东西?(不是实际的密度函数，因为面积不需要积分为 1.)以下问题类似:ggplot2:带有正态曲线的直方图，并且用户自己回答了缩放的想法..count.. 在 geom_density() 内部.然而，这似乎不寻常.

Is there a method to overlay something analogous to a density curve when the vertical axis is frequency or relative frequency? (Not an actual density function, since the area need not integrate to 1.) The following question is similar: ggplot2: histogram with normal curve, and the user self-answers with the idea to scale ..count.. inside of geom_density(). However this seems unusual.

以下代码产生过度膨胀的密度"线.

The following code produces an overinflated "density" line.

df1            <- data.frame(v = rnorm(164, mean = 9, sd = 1.5))
b1             <- seq(4.5, 12, by = 0.1)
hist.1a        <- ggplot(df1, aes(v)) + 
                    stat_bin(aes(y = ..count..), color = "black", fill = "blue",
                             breaks = b1) + 
                    geom_density(aes(y = ..count..))
hist.1a

推荐答案

@joran 的回复/评论让我开始思考合适的缩放因子是什么.为了后代，这是结果.

@joran's response/comment got me thinking about what the appropriate scaling factor would be. For posterity's sake, here's the result.

当纵轴是频率(又名计数)时

因此，以 bin 计数测量的垂直轴的比例因子是

Thus, the scaling factor for a vertical axis measured in bin counts is

在这种情况下，当 N = 164 和 bin 宽度为 0.1 时，平滑线中 y 的美感应该是:

In this case, with N = 164 and the bin width as 0.1, the aesthetic for y in the smoothed line should be:

y = ..density..*(164 * 0.1)

因此，以下代码生成了一条密度"线，该线针对以频率(又名计数)测量的直方图进行了缩放.

Thus the following code produces a "density" line scaled for a histogram measured in frequency (aka count).

df1            <- data.frame(v = rnorm(164, mean = 9, sd = 1.5))
b1             <- seq(4.5, 12, by = 0.1)
hist.1a        <- ggplot(df1, aes(x = v)) + 
                    geom_histogram(aes(y = ..count..), breaks = b1, 
                                   fill = "blue", color = "black") + 
                    geom_density(aes(y = ..density..*(164*0.1)))
hist.1a

当纵轴为相对频率时

使用上面的，我们可以写

Using the above, we could write

hist.1b        <- ggplot(df1, aes(x = v)) + 
                    geom_histogram(aes(y = ..count../164), breaks = b1, 
                                   fill = "blue", color = "black") + 
                    geom_density(aes(y = ..density..*(0.1)))
hist.1b

当纵轴为密度时

hist.1c        <- ggplot(df1, aes(x = v)) + 
                    geom_histogram(aes(y = ..density..), breaks = b1, 
                                   fill = "blue", color = "black") + 
                    geom_density(aes(y = ..density..))
hist.1c

这篇关于“密度"直方图上的曲线叠加，其中纵轴是频率(又名计数)还是相对频率?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！