r - 无法在 R 中使用 ggplot2 调整对数曲线

Question

我试图用 ggplot2 绘制一条可调对数曲线.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，无论什么极值我都放了start = list(a = 1, b = 1)线，我根本无法调整对数曲线。

Answer 1

试试这个启用来自 nls() 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, 1),algorithm = "port"
    ),
    se = FALSE
  )
print(graph)


# ggplot graph plotting 2
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 = 999, b = 999),
      lower = c(999, 999),
      upper = c(999, 999),algorithm = "port"
    ),
    se = FALSE
  )
print(graph)

输出:


或这个:

# ggplot graph plotting 3
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(10, 20),algorithm = "port"
    ),
    se = FALSE
  )
print(graph)

输出: