我能'；t使用text2vec为我的测试数据创建tf idf矩阵

我一直在关注和做，就像我在训练集上做的一样，但它一直在说同样的事情。有人知道这是怎么回事吗

> #Construct sample document-term matrix con el vectorizer inicial
> sample.it <- itoken(rawsample$Abstract, 
+                     preprocessor = prep_fun, 
+                     tokenizer = tok_fun, 
+                     ids = rawsample$id,
+                     progressbar = F) 
> sample.dtm <- create_dtm (sample.it, vectorizer, vtype = "dgTMatrix", progressbar = FALSE)
> sample.tfidf <- TfIdf$new() #define tfidf model
> sample.tfidf <- fit_transform(sample.dtm, tfidf)
Error in fit_transform.Matrix(sample.dtm, tfidf) : 
  inherits(model, "mlapiTransformation") is not TRUE
> sample.tfidf  = create_dtm(sample.it, vectorizer, vtype = "dgTMatrix", progressbar = FALSE) %>% 
+   transform(tfidf)
Error in transform.Matrix(., tfidf) : 
  inherits(model, "mlapiTransformation") is not TRUE

#构造示例文档术语矩阵con el矢量器
>sample.it sample.dtm sample.tfidf sample.tfidf sample.tfidf=create_dtm（sample.it，矢量器，vtype=“dgTMatrix”，progressbar=FALSE）%>%
+转换（tfidf）
转换矩阵（，tfidf）中出错：
继承（模型，“mlapiTransformation”）不正确

sample.tfidf <- TfIdf$new() #define tfidf model
sample.tfidf <- fit_transform(sample.dtm, tfidf)

model =  TfIdf$new() #define tfidf model
sample.tfidf = fit_transform(sample.dtm, model)