我想从pyspark Dataframe 中获取每列的最大长度。
以下是示例 Dataframe ：

from pyspark.sql.types import StructType,StructField, StringType, IntegerType

data2 = [("James","","Smith","36636","M",3000),
    ("Michael","Rose","","40288","M",4000),
    ("Robert","","Williams","42114","M",4000),
    ("Maria","Anne","Jones","39192","F",4000),
    ("Jen","Mary","Brown","","F",-1)
  ]

schema = StructType([ \
    StructField("firstname",StringType(),True), \
    StructField("middlename",StringType(),True), \
    StructField("lastname",StringType(),True), \
    StructField("id", StringType(), True), \
    StructField("gender", StringType(), True), \
    StructField("salary", IntegerType(), True) \
  ])
 
df = spark.createDataFrame(data=data2,schema=schema)

我尝试实现solution provided in Scala，但无法转换它。