无法在 R 中使用 ggplot2 调整对数曲线

问题描述

我正在尝试使用 ggplot2 绘制可调整的对数曲线。从各种 Stack Overflow 帖子中，我能够创建这个：

key <- c(1,2,300)
value <- c(10,20,300)
dummyData <- data.frame(key,value)

# ggplot graph plotting
graph <- ggplot(dummyData,mapping = aes(x=key,y=value))+
  stat_smooth(
    method = 'nls',formula = 'y ~ a * log(x) + b',method.args = list(
      start = list(a = 1,b = 1)
    ),se = FALSE
    )
print(graph)

然而，不管我把start = list(a = 1,b = 1)线放在什么极值上，我根本无法调整对数曲线。

解决方法

尝试启用 nls() 中的下/上选项。如您所见，曲线发生了变化：

library(ggplot2)
# ggplot graph plotting 1
graph <- ggplot(dummyData,mapping = aes(x=key,y=value))+
  stat_smooth(
    method = 'nls',formula = 'y ~ a * log(x) + b',method.args = list(
      start = list(a = 1,b = 1),lower = c(1,1),upper = c(1,algorithm = "port"
    ),se = FALSE
  )
print(graph)


# ggplot graph plotting 2
graph <- ggplot(dummyData,method.args = list(
      start = list(a = 999,b = 999),lower = c(999,999),upper = c(999,se = FALSE
  )
print(graph)

输出：

或者这个：

# ggplot graph plotting 3
graph <- ggplot(dummyData,upper = c(10,20),se = FALSE
  )
print(graph)

输出：