在ggplot2中绘制离散(或不连续)函数。

I have the following function, which I would like to plot using ggplot:

我有下面的函数，我想用ggplot来绘图:

f(x) = 3/4 for x between 0 and 1; 1/4 for x between 2 and 3; and 0 elsewhere.

f(x) = 3/4, x在0和1之间;1/4的x在2到3之间;和0。

I have come up with the following R code:

我已经提出了以下的R代码:

eq<-function(x) {
    if(x>=0 && x<=1) {
        y<-3/4
    } else if(x>=2 && x<=3) {
        y<-1/4
    } else {
    y<-0
    }
return(y)
}

library(ggplot2)

ggplot(data.frame(x=c(-5,5)), aes(x)) + stat_function(fun=eq)

However, this results in a plot with only a horizontal line centered on 0. What have I done wrong?

然而，这只会导致一个以0为中心的水平线。我做错了什么?

2 个解决方案

#1

The function should be "vectorized", i.e., accept a vector as argument.

函数应该是“向量化的”，即。，接受一个向量作为参数。

eq <- function(x) 
  ifelse( x>=0 & x<=1, 3/4,
  ifelse( x>=2 & x<=3, 1/4, 0 ))
ggplot(data.frame(x=c(-5,5)), aes(x)) + 
  stat_function(fun=eq, geom="step")

#2

I think this is another place where either switch could be used to great effect, or something along the lines of
ysteps <- c(.75,.25,0) xsteps <- c(1,2,3) y <- ysteps[which(x >= xsteps)]

我认为这是另一个开关可以用来产生巨大影响的地方，或者类似于ysteps <- c(.75，.25,0) xsteps <- c(1,2,3) y <- ysteps (x >= xsteps)的地方。

Please feel free to edit this so it's correct -- my brain is slow and I don't have R available right now.

请随意编辑，这是正确的，我的大脑是慢的，我现在没有R。

#1