Split Spark DataFrame into two DataFrames (70% and 30% ) based on id column by preserving order

问题

I have a spark dataframe which is like

id  start_time   feature
1   01-01-2018   3.567
1   01-02-2018   4.454
1   01-03-2018   6.455
2   01-02-2018   343.4
2   01-08-2018   45.4
3   02-04-2018   43.56
3   02-07-2018   34.56
3   03-07-2018   23.6

I want to be able to split this into two dataframes based on the id column.So I should groupby the id column, sort by start_time and take 70% of the rows into one dataframe and 30% of the rows into another dataframe by preserving the order.The result should look like:

Dataframe1:
id  start_time   feature
1   01-01-2018   3.567
1   01-02-2018   4.454
2   01-02-2018   343.4
3   02-04-2018   43.56
3   02-07-2018   34.56

Dataframe2:
1   01-03-2018   6.455
2   01-08-2018   45.4
3   03-07-2018   23.6

I am using Spark 2.0 with python. What is the best way to implement this?

回答1:

The way I had to do it was to create two windows:

w1 =  Window.partitionBy(df.id).orderBy(df.start_time)
w2 =  Window.partitionBy(df.id)

df = df.withColumn("row_number",F.row_number().over(w1))\
                     .withColumn("count",F.count("id").over(w2))\
                     .withColumn("percent",(F.col("row_number")/F.col("count")))
train = df.filter(df.percent<=0.70)
test = df.filter(df.percent>0.70)

来源：https://stackoverflow.com/questions/52958225/split-spark-dataframe-into-two-dataframes-70-and-30-based-on-id-column-by-p