在 R 中绘制逻辑回归的预测线

Question

我已经在 R 中建立了一个逻辑回归模型，并成功地绘制了模型的点以显示数据集中的关系。我无法显示预测的折线图。该模型根据初始住院时间（以天为单位）预测医院的再入院率。这是我的代码：

mydata <- read.csv(file = 'C:\\Users\\nickg\\Downloads\\3kfid8emf9rkc9ek30sf\\medical_clean.csv', header=TRUE)[,c("Initial_days","ReAdmis")]
head(mydata)
mydata$ReAdmis.f <- factor(mydata$ReAdmis)
logfit <- glm(mydata$ReAdmis.f ~ mydata$Initial_days, data = mydata, family = binomial)
summary(logfit)
range(mydata$Initial_days)
xweight <- seq(0, 79.992, .008)
yweight <- predict(logfit, list(xweight),  type = "response")
plot(mydata$Initial_days, mydata$ReAdmis.f, pch = 16, xlab = "Initial Days", ylab = "ReAdmission Y/N")
lines(xweight, yweight)

如您所见，我设置了 xweight 和 yweight 描述的模型和范围，但该行没有显示任何内容。

Answer 1

始终为此使用curve：

plot(ReAdmis.f ~ Initial_days, data = mydata, 
     pch = 16, xlab = "Initial Days", ylab = "ReAdmission Y/N")

curve(predict(logfit, newdata = data.frame(Initial_days = x), 
#x is created by the curve function based on the plot's x limits 
#note that newdata must contain the x variable with exactly the same name as in the original data
              type = "response"),
      add = TRUE)

但是，这里的问题可能是您的 y 变量是一个因子变量（如果您有两个水平，则内部值为 1 和 2），而逻辑回归预测始终在区间 [0, 1] 中。在运行代码之前，您应该将ReAdmis.f 转换为 0/1 整数值。