使用stat_function在ggplot2中绘制部分阴影的正常曲线(Using stat_function to draw partially shaded normal curve in ggplot2)

 我在R中是一个很大的初学者，我很困惑ggplot在创建普通曲线时如何使用变量“x”。 
 
 我的情况是这样的。 我试图在给定特定方法和标准偏差的情况下绘制正态曲线，并且在没有数据的情况下，我看到的最常见的方法如下： 
 
score = 1800
m = 1500
std = 300

ggplot(data.frame(x = c(300, 2700)), aes(x = x)) + stat_function(fun = 
     dnorm, args = list(mean = m, sd = std)) + scale_x_continuous(name 
     = "Score", breaks = seq(300, 2700, std))
 
 我想遮蔽曲线的特定区域，所以使用Internet我创建了一个函数如下： 
 
funcShaded <- function(x) {
    y = dnorm(x, mean = m, sd = std)
    y[x < score] <- NA
    return(y)
}
 
 然后使用p + stat_function(fun = funcShaded, geom="area", fill="#84CA72", alpha=.2)向我的曲线添加一个图层p + stat_function(fun = funcShaded, geom="area", fill="#84CA72", alpha=.2) 
 
 这可以创建我想要的图形。 但是，我有两个问题。 首先，当我打破代码时 
 
data.frame(x = c(300, 2700))
 
 如您所期望的那样创建一个两项数据框，这样如何能够用于创建x轴值，并进一步传递给要正确使用的函数（读取。就好像它是一个值列表）？ 
 
 其次，我现在想要稍后重新使用这个函数来根据不同的分数（例如score2 = 1630 ）填充曲线下的其他区域，并且认为我可以将另一个变量添加到funcShaded以通过分数（即funcShaded <- function(x, score))然后按如下方式调用我的stat_function ： p + stat_function(fun = funcShaded(x, score2), ...)但是： 
 
 
 
 我不确定这种语法是否有效 
 
 
 似乎x变量从未使用此代码显式“创建”，因为它不会出现在我的环境中，当我尝试此代码时，我得到错误：找不到对象'x' 
 
 
 所以我想我只是好奇'x'在这种情况下是如何工作的，如果我应该按照我想要的方式创造它。 

I'm a big beginner in R and am very confused as to how ggplot is using variable "x" when creating normal curves.
 
My situation is this. I'm trying to plot normal curves given specific means and standard deviations and in the absence of data the most common way I've seen to do this is as follows:
 
score = 1800
m = 1500
std = 300

ggplot(data.frame(x = c(300, 2700)), aes(x = x)) + stat_function(fun = 
     dnorm, args = list(mean = m, sd = std)) + scale_x_continuous(name 
     = "Score", breaks = seq(300, 2700, std))
 
I wanted to shade a specific area of the curve so using the Internet I created a function as follows:
 
funcShaded <- function(x) {
    y = dnorm(x, mean = m, sd = std)
    y[x < score] <- NA
    return(y)
}
 
And then added a layer to my curve with p + stat_function(fun = funcShaded, geom="area", fill="#84CA72", alpha=.2)
 
This works to create the graph I desire. However, I have 2 questions about this. First, when I break the code down
 
data.frame(x = c(300, 2700))
 
creates a two item dataframe as you would expect so how is this capable to being used to create x-axis values and, further, to be passed to the function to be used appropriately (read. as if it were a list of values)?
 
Second, I now want to re-use this function later to fill in other area under the curve based on a different score (e.g. score2 = 1630) and was thinking I could just add another variable to funcShaded to pass score (i.e. funcShaded <- function(x, score)) and then call my stat_function as follows: p + stat_function(fun = funcShaded(x, score2), ...) but:
 
 
 
I'm not sure this syntax will work 
 
 
It seems like the x variable is never explicitly "created" with this code because it doesn't show up in my Environment and when I try this code I get Error: object 'x' not found
 
 
So I guess I'm just curious as to how 'x' is working in this situation and if I should be creating it differently given what I want to do.

原文：https://stackoverflow.com/questions/48753007