R：使用 ggplot2 绘制多个函数

我需要绘制多个显式函数定义以直观地比较它们。

考虑函数族：

fun.1 <- function(x) { 1 / ( 0.01 + x) }
fun.2 <- function(x) { 1 / ( 0.1 + x) }
fun.3 <- function(x) { 1 / ( 0.3 + x) }

这个想法是绘制评估这些函数的结果 关于以下输入：

xs = c(1, 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024, 2048)

目前，我的代码是：

library(ggplot2)
library(dplyr)

xs = c(1, 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024, 2048)

fun.1 <- function(x) { 1 / ( 0.01 + x) }
fun.2 <- function(x) { 1 / ( 0.1 + x) }
fun.3 <- function(x) { 1 / ( 0.3 + x) }

base <- ggplot(data.frame(x = xs), aes(x=as.factor(x)))

base + theme_classic() +
       theme(
          legend.position = c(.95, .95),
          legend.justification = c("right", "top"),
          legend.box.just = "right",
          legend.margin = margin(6, 6, 6, 6)
          ) +
       geom_function(fun = fun.1, colour = "red") + 
       geom_function(fun = fun.2, colour = "blue") +
       geom_function(fun = fun.3, colour = "yellow") +
       scale_x_discrete(name = "Input",
                        breaks = xs) +
       scale_y_discrete(name = "Growth")

结果是这样的

现在这看起来很难看，我无法让图例出现并且有警告：

Multiple drawing groups in `geom_function()`. Did you use the correct `group`, `colour`, or `fill` aesthetics?
Multiple drawing groups in `geom_function()`. Did you use the correct `group`, `colour`, or `fill` aesthetics?
Multiple drawing groups in `geom_function()`. Did you use the correct `group`, `colour`, or `fill` aesthetics?

我想要的风格就像this。理想情况下，这些点应该是可见的 并由连续曲线连接。

问题是，创建具有多个函数且样式如下的绘图的最佳方法是什么this ?

你可以只lapply()在某些东西上，如果它自动添加到 ggplot 中，因为它是一个列表。仅当 lapply 循环的输出是 ggplot 能够理解的内容（例如 geoms）时，这才有用。

下面的示例假设可以使用您提供的命名结构找到相关函数。

library(ggplot2)
library(dplyr)
#> 
#> Attaching package: 'dplyr'
#> The following objects are masked from 'package:stats':
#> 
#>     filter, lag
#> The following objects are masked from 'package:base':
#> 
#>     intersect, setdiff, setequal, union

xs = c(1, 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024, 2048)

fun.1 <- function(x) { 1 / ( 0.01 + x) }
fun.2 <- function(x) { 1 / ( 0.1 + x) }
fun.3 <- function(x) { 1 / ( 0.3 + x) }

ggplot(data.frame(x = xs), aes(x=x)) + 
  lapply(1:3, function(i) {
    fun_name <- paste0("fun.", i)
    fun <- get(fun_name)
    line <- geom_function(fun = fun,
                          aes(colour = fun_name))
    points <- geom_point(aes(y = fun(xs), colour = fun_name))
    list(line, points)
  }) +
  scale_x_log10(breaks = xs, name = "Input") +
  scale_y_continuous(name = "Growth") +
  theme_classic() +
  theme(
    legend.position = c(.95, .95),
    legend.justification = c("right", "top"),
    legend.box.just = "right",
    legend.margin = margin(6, 6, 6, 6)
  )

^{Created on 2020-12-07 by the reprex package (v0.3.0)}

值得注意的是，虽然你的情节在几乎所有方面似乎都是连续的，但你添加了_discrete()我不明白的位置尺度的变体。我将所有内容都转换为数字。