使用插入符号创建混淆矩阵

Question

I want to create a confusion matrix and need to extract Precision as a vector with the following sample:

true_values <- sample(c("Dog", "Cat"), 10000, replace = TRUE,
prob = c(0.3, 0.7))
predicted_values <- true_values
predicted_values[sample.int(10000, 4000)] <-
sample(c("Dog", "Cat"), 4000, replace = TRUE, prob = c(0.3, 0.7))

Answer 1

You can do it like this, assuming positive class is Dog :

cm = confusionMatrix(table(predicted_values,true_values),
positive="Dog",mode="prec_recall")

cm$byClass["Precision"]
Precision 
0.7264901