我在我的一个项目中使用了caret函数的"train()",我想添加一个"自定义指标"F1-score。我查看了这个网址caret包,但我不明白如何使用可用的参数来构建这个评分。
这里有一个自定义指标的例子:
## Example with a custom metric
madSummary <- function (data,
lev = NULL,
model = NULL) {
out <- mad(data$obs - data$pred,
na.rm = TRUE)
names(out) <- "MAD"
out
}
robustControl <- trainControl(summaryFunction = madSummary)
marsGrid <- expand.grid(degree = 1, nprune = (1:10) * 2)
earthFit <- train(medv ~ .,
data = BostonHousing,
method = "earth",
tuneGrid = marsGrid,
metric = "MAD",
maximize = FALSE,
trControl = robustControl)
更新:我尝试了你的代码,但问题是它不能处理多个类别,比如下面的代码(显示F1得分,但是它很奇怪)。我不确定,但我认为F1_score函数只能用于二进制类别。
library(caret)
library(MLmetrics)
set.seed(346)
dat <- iris
## See http://topepo.github.io/caret/training.html#metrics
f1 <- function(data, lev = NULL, model = NULL) {
print(data)
f1_val <- F1_Score(y_pred = data$pred, y_true = data$obs)
c(F1 = f1_val)
}
# Split the Data into .75 input
in_train <- createDataPartition(dat$Species, p = .70, list = FALSE)
trainClass <- dat[in_train,]
testClass <- dat[-in_train,]
set.seed(35)
mod <- train(Species ~ ., data = trainClass ,
method = "rpart",
metric = "F1",
trControl = trainControl(summaryFunction = f1,
classProbs = TRUE))
print(mod)
我也编写了一个手动F1分数的函数,只需要输入混淆矩阵即可。(我不确定在 "summaryFunction" 中是否可以使用混淆矩阵)
F1_score <- function(mat, algoName){
##
## Compute F1-score
##
# Remark: left column = prediction // top = real values
recall <- matrix(1:nrow(mat), ncol = nrow(mat))
precision <- matrix(1:nrow(mat), ncol = nrow(mat))
F1_score <- matrix(1:nrow(mat), ncol = nrow(mat))
for(i in 1:nrow(mat)){
recall[i] <- mat[i,i]/rowSums(mat)[i]
precision[i] <- mat[i,i]/colSums(mat)[i]
}
for(i in 1:ncol(recall)){
F1_score[i] <- 2 * ( precision[i] * recall[i] ) / ( precision[i] + recall[i])
}
# We display the matrix labels
colnames(F1_score) <- colnames(mat)
rownames(F1_score) <- algoName
# Display the F1_score for each class
F1_score
# Display the average F1_score
mean(F1_score[1,])
}
train
输出中使用其结果。您能详细说明一下吗? - pbahr