I tried below code but its not working:
df=df.withColumn("cars", typedLit(Map.empty[String, String]))
Gives the error: NameError: name 'typedLit' is not defined
如何在PySpark中向DataFrame添加空map<string,string>类型的列？
2
人关注
3
个评论
samkart
：
那是在使用前进口的吗？
@samkart 不，我不能为这个导入什么东西
Rahul Diggi
发布于
2022-06-23
2
个回答
Steven
发布于
2022-06-23
已采纳
0
人赞同
创建一个空列，并将其铸成你需要的类型。
from pyspark.sql import functions as F, types as T
df = df.withColumn("cars", F.lit(None).cast(T.MapType(T.StringType(), T.StringType())))
df.select("cars").printSchema()
|-- cars: map (nullable = true)
| |-- key: string
| |-- value: string (valueContainsNull = true)
mazaneicha
发布于
2022-06-23
0
人赞同
也许你可以用
pyspark.sql.functions.expr
:
>>> from pyspark.sql.functions import *
>>> df.withColumn("cars",expr("map()")).printSchema()
|-- col1: string (nullable = true)
|-- cars: map (nullable = false)
| |-- key: string
| |-- value: string (valueContainsNull = false)
EDIT:
If you'd like your map to have keys and/or values of a non-trivial type (not map<string,string> as your question's title says), some casting becomes unavoidable, I'm afraid. For example:
>>> df.withColumn("cars",create_map(lit(None).cast(IntegerType()),lit(None).cast(DoubleType()))).printSchema()
|-- col1: string (nullable = true)
|-- cars: map (nullable = false)