qqplot + stat_smooth错误

Question

我试图用nls模型来绘制我的数值并用曲线拟合它们。但我得到了一个错误，说我的变量没有起始值。

conc <- c(1.83, 3.66, 7.32, 14.65, 29.30, 58.59, 117.19, 468.75, 937.5, 1875, 3750)  
avg <- c(0.02, 0.03, 0.05, 0.09, 0.23, 0.40, 0.60, 0.79, 0.98, 0.82, 1)

DataSet <- data.frame(conc, avg)

ggplot(DataSet, aes(x = conc, y = avg)) + 
  geom_point() +
  scale_x_log10() + 
  stat_smooth(aes(x=conc, y = avg), method = "nls", 
              formula = "avg~Emax*(conc^Hill)/((EC50^Hill)+(conc^Hill))",
              method.args=list(start=c(Emax = 1, EC50 = 100, Hill = 2)),
              se = FALSE)

# Warning message:
# Computation failed in `stat_smooth()`:
# parameters without starting value in 'data': avg, conc 

Answer 1

您需要在公式中调整x，因为scale_x_log10()已用于axis。因此，log10的逆(例如^10)应该用于公式中的x。

解决办法如下：

library(ggplot2)

ggplot(DataSet, aes(x = conc, y = avg)) + 
  geom_point() +
  scale_x_log10() +
  stat_smooth(method = "nls", 
              formula = y~Emax*((10^x)^Hill)/((EC50^Hill)+((10^x)^Hill)),
              method.args=list(start=c(Emax = 1, EC50 = 100, Hill = 2)),
              se = FALSE)

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