如何在PySpark中对分组对象中的列进行插值？

from pyspark.sql import SparkSession
from pyspark.sql.functions import col, when, last
from pyspark.sql.window import Window

spark = SparkSession.builder.getOrCreate()

data = [(1, 'A', 10),
        (1, 'B', None),
        (1, 'C', 30),
        (2, 'A', None),
        (2, 'B', 50),
        (2, 'C', 60),
        (3, 'A', 70),
        (3, 'B', None),
        (3, 'C', 90)]

df = spark.createDataFrame(data, ['group', 'category', 'value'])

window_spec = Window.partitionBy('group').orderBy('category')

df = df.withColumn('value', when(col('value').isNull(), last(col('value'), True).over(window_spec)).otherwise(col('value')))

df.show()