我试图在虹膜数据集上使用nnet，但我不知道如何解决下面显示的错误 . 任何帮助赞赏 . 谢谢 .
library(nnet)
attach(iris)
library(caret)
set.seed(3456)
trainIndex <- createDataPartition(iris$Species, p = .8,
list = FALSE,
times = 1)
irisTrain <- iris[ trainIndex,]
irisTest <- iris[-trainIndex,]
irispred <- nnet(species ~ ., data=irisTrain, size=10)
predicted <- predict(irispred,irisTest,type="class")
Error in model.frame.default(formula = species ~ ., data = irisTrain) : variable lengths differ (found for 'Sepal.Length')