给出一个带有数组列表的数据框
Schema
|-- items: array (nullable = true)
| |-- element: struct (containsNull = true)
| | |-- name: string (nullable = true)
| | |-- quantity: string (nullable = true)
+-------------------------------+
|items |
+-------------------------------+
|[[A, 1], [B, 1], [C, 2]] |
---------------------------------
我如何获取字符串:
+-------------------------------+
|items |
+-------------------------------+
|A, 1, B, 1, C, 2 |
---------------------------------
尝试:
df.withColumn('item_str', concat_ws(" ", col("items"))).select("item_str").show(truncate = False)
错误:
: org.apache.spark.sql.AnalysisException: cannot resolve 'concat_ws(' ', `items`)' due to data type mismatch: argument 2 requires (array<string> or string) type, however, '`items`' is of array<struct<name:string,quantity:string>> type.;;
您可以结合使用transform和array_join内置功能来实现:
from pyspark.sql.functions import expr
df.withColumn("items", expr("array_join(transform(items, \
i -> concat_ws(',', i.name, i.quantity)), ',')"))
我们使用transform在项目之间进行迭代,并将每个项目转换为name,quantity
字符串。然后,我们使用array_join来连接由transform返回的所有项目,并以逗号分隔。
在此处爆炸可能有用
import org.apache.spark.sql.functions._
df.select(explode("items")).select("col.*")