Efficient column processing in PySpark

后端 未结 3 1743
死守一世寂寞
死守一世寂寞 2021-01-15 13:46

I have a dataframe with a very large number of columns (>30000).

I\'m filling it with 1 and 0 based on the first column like this:

3条回答
  •  执笔经年
    2021-01-15 13:51

    withColumn is already distributed so a faster approach would be difficult to get other than what you already have. you can try defining a udf function as following

    from pyspark.sql import functions as f
    from pyspark.sql import types as t
    
    def containsUdf(listColumn):
        row = {}
        for column in list_of_column_names:
            if(column in listColumn):
                row.update({column: 1})
            else:
                row.update({column: 0})
        return row
    
    callContainsUdf = f.udf(containsUdf, t.StructType([t.StructField(x, t.StringType(), True) for x in list_of_column_names]))
    
    df.withColumn('struct', callContainsUdf(df['list_column']))\
        .select(f.col('list_column'), f.col('struct.*'))\
        .show(truncate=False)
    

    which should give you

    +-----------+---+---+---+
    |list_column|Foo|Bar|Baz|
    +-----------+---+---+---+
    |[Foo, Bak] |1  |0  |0  |
    |[Bar, Baz] |0  |1  |1  |
    |[Foo]      |1  |0  |0  |
    +-----------+---+---+---+
    

    Note: list_of_column_names = ["Foo","Bar","Baz"]

提交回复
热议问题