如何在sparklyr中训练ML模型并在另一个数据帧上预测新值？

Consider the following example

请考虑以下示例

dtrain <- data_frame(text = c("Chinese Beijing Chinese",
                              "Chinese Chinese Shanghai",
                              "Chinese Macao",
                              "Tokyo Japan Chinese"),
                     doc_id = 1:4,
                     class = c(1, 1, 1, 0))

dtrain_spark <- copy_to(sc, dtrain, overwrite = TRUE)

> dtrain_spark
# Source:   table<dtrain> [?? x 3]
# Database: spark_connection
  text                     doc_id class
  <chr>                     <int> <dbl>
1 Chinese Beijing Chinese       1     1
2 Chinese Chinese Shanghai      2     1
3 Chinese Macao                 3     1
4 Tokyo Japan Chinese           4     0
dtra