caret::predict giving Error: $ operator is invalid for atomic vectors

Question

这让我发疯了，我整天都在浏览类似的帖子，但似乎无法解决我的问题。我有一个经过训练并存储为 model 的朴素贝叶斯模型。我正在尝试使用 newdata 数据框进行预测，但我一直收到错误 Error: $ operator is invalid for atomic vectors。这是我的运行：stats::predict(model, newdata = newdata) 其中 newdata 是另一个数据框的第一行：new data <- pbp[1, c("balls", "strikes", "outs_when_up", "stand", "pitcher", "p_throws", "inning")]

class(newdata) 给出 [1] "tbl_df" "tbl" "data.frame".

Answer 1

问题出在所使用的数据上。它应该与训练中使用的 levels 匹配。例如。如果我们使用从 trainingData 到 predict 的其中一行，它确实有效

predict(model, head(model$trainingData, 1))
#[1] Curveball
#Levels: Changeup Curveball Fastball Sinker Slider

通过检查两个数据集的str，训练中的某些factor列是character class

str(model$trainingData)
'data.frame':   1277525 obs. of  7 variables:
 $ pitcher     : Factor w/ 1390 levels "112526","115629",..: 277 277 277 277 277 277 277 277 277 277 ...
 $ stand       : Factor w/ 2 levels "L","R": 1 1 2 2 2 2 2 1 1 1 ...
 $ p_throws    : Factor w/ 2 levels "L","R": 2 2 2 2 2 2 2 2 2 2 ...
 $ balls       : num  0 1 0 1 2 2 2 0 0 0 ...
 $ strikes     : num  0 0 0 0 0 1 2 0 1 2 ...
 $ outs_when_up: num  1 1 1 1 1 1 1 2 2 2 ...
 $ .outcome    : Factor w/ 5 levels "Changeup","Curveball",..: 3 4 1 4 1 5 5 1 1 5 ...

str(newdata)
tibble [1 × 6] (S3: tbl_df/tbl/data.frame)
 $ balls       : int 3
 $ strikes     : int 2
 $ outs_when_up: int 1
 $ stand       : chr "R"
 $ pitcher     : int 605200
 $ p_throws    : chr "R"

一个选项是使 levels 与 factor class

相同

nm1 <- intersect(names(model$trainingData), names(newdata))
nm2 <- names(which(sapply(model$trainingData[nm1], is.factor)))
newdata[nm2] <- Map(function(x, y) factor(x, levels = levels(y)), newdata[nm2], model$trainingData[nm2])

现在做 prediction

predict(model, newdata)
#[1] Sinker
#Levels: Changeup Curveball Fastball Sinker Slider

caret::predict giving Error: $ operator is invalid for atomic vectors

caret::predict giving Error: $ operator is invalid for atomic vectors

r

r-caret

naivebayes