问题
Can someone please share how one can convert a dataframe to an RDD?
回答1:
Simply:
val rows: RDD[Row] = df.rdd
回答2:
Use df.map(row => ...) to convert the dataframe to a RDD if you want to map a row to a different RDD element. For example
df.map(row => (row(1), row(2)))
gives you a paired RDD where the first column of the df is the key and the second column of the df is the value.
回答3:
I was just looking for my answer and found this post.
Jean's answer to absolutely correct,adding on that "df.rdd" will return a RDD[Rows]. I need to apply split() once i get RDD. For that we need to convert RDD[Row} to RDD[String]
val opt=spark.sql("select tags from cvs").map(x=>x.toString()).rdd
来源：https://stackoverflow.com/questions/32531224/how-to-convert-dataframe-to-rdd-in-scala