pyspark 'DataFrame' object has no attribute '_get_object_id'

问题

I am trying to run some code, but getting error:

'DataFrame' object has no attribute '_get_object_id'

The code:

items = [(1,12),(1,float('Nan')),(1,14),(1,10),(2,22),(2,20),(2,float('Nan')),(3,300),
         (3,float('Nan'))]

sc = spark.sparkContext
rdd = sc.parallelize(items)
df = rdd.toDF(["id", "col1"])

import pyspark.sql.functions as func
means = df.groupby("id").agg(func.mean("col1"))

# The error is thrown at this line
df = df.withColumn("col1", func.when((df["col1"].isNull()), means.where(func.col("id")==df["id"])).otherwise(func.col("col1")))

回答1:

You can't reference a second spark DataFrame inside a function, unless you're using a join. IIUC, you can do the following to achieve your desired result.

Suppose that means is the following:

#means.show()
#+---+---------+
#| id|avg(col1)|
#+---+---------+
#|  1|     12.0|
#|  3|    300.0|
#|  2|     21.0|
#+---+---------+

Join df and means on the id column, then apply your when condition

from pyspark.sql.functions import when

df.join(means, on="id")\
    .withColumn(
        "col1",
        when(
            (df["col1"].isNull()), 
            means["avg(col1)"]
        ).otherwise(df["col1"])
    )\
    .select(*df.columns)\
    .show()
#+---+-----+
#| id| col1|
#+---+-----+
#|  1| 12.0|
#|  1| 12.0|
#|  1| 14.0|
#|  1| 10.0|
#|  3|300.0|
#|  3|300.0|
#|  2| 21.0|
#|  2| 22.0|
#|  2| 20.0|
#+---+-----+

But in this case, I'd actually recommend using a Window with pyspark.sql.functions.mean:

from pyspark.sql import Window
from pyspark.sql.functions import col, mean

df.withColumn(
    "col1",
    when(
        col("col1").isNull(), 
        mean("col1").over(Window.partitionBy("id"))
    ).otherwise(col("col1"))
).show()
#+---+-----+
#| id| col1|
#+---+-----+
#|  1| 12.0|
#|  1| 10.0|
#|  1| 12.0|
#|  1| 14.0|
#|  3|300.0|
#|  3|300.0|
#|  2| 22.0|
#|  2| 20.0|
#|  2| 21.0|
#+---+-----+

回答2:

I think you are using Scala API, in which you use (). In PySpark, use [] instead.

来源：https://stackoverflow.com/questions/57363618/pyspark-dataframe-object-has-no-attribute-get-object-id

标签

python

dataframe

apache-spark

pyspark