我正在尝试对嵌套列进行匿名/哈希处理,但尚未成功。架构看起来像这样:
-- abc: struct (nullable = true)
| |-- xyz: struct (nullable = true)
| | |-- abc123: string (nullable = true)
| | |-- services: struct (nullable = true)
| | | |-- service: array (nullable = true)
| | | | |-- element: struct (containsNull = true)
| | | | | |-- type: string (nullable = true)
| | | | | |-- subtype: string (nullable = true)
我需要更改(匿名/哈希)
type
列的值。
withField
可用于更新结构体字段。
假设这是您的输入数据框(对应于您提供的架构):
from pyspark.sql import Row
df = spark.createDataFrame([
Row(abc=Row(xyz=Row(abc123="value123", services=[Row(type="type1", subtype="subtype1")])))
])
df.show(truncate=False)
#+---------------------------------+
#|abc |
#+---------------------------------+
#|{{value123, [{type1, subtype1}]}}|
#+---------------------------------+
您可以在数组 transform
上使用
services
来哈希每个结构体元素的字段 type
(这里我使用 xxhash64
函数来说明),如下所示:
import pyspark.sql.functions as F
df2 = df.withColumn(
"abc",
F.col("abc").withField(
"xyz",
F.col("abc.xyz").withField(
"services",
F.expr("transform(abc.xyz.services, x -> struct(xxhash64(x.type) as type, x.subtype))")
)
)
)
df2.show(truncate=False)
#+-----------------------------------------------+
#|abc |
#+-----------------------------------------------+
#|{{value123, [{2134479862461603894, subtype1}]}}|
#+-----------------------------------------------+
对于较旧的 Spark 版本,您需要重新创建整个结构才能更新字段,这在存在许多嵌套字段时变得乏味。在你的情况下,它会是这样的:
df2 = df.withColumn(
"abc",
F.struct(
F.struct(
F.col("abc.xyz.abc123"),
F.expr(
"transform(abc.xyz.services, x -> struct(xxhash64(x.type) as type, x.subtype))"
).alias("services")
).alias("xyz")
)
)
使用
pyspark-nested-functions库中的
hash
函数,您可以使用 "abc.xyz.services.type"
:散列任何嵌套字段(例如
hash_field(df, "abc.xyz.services.type")
)
from pyspark.sql import Row
df = spark.createDataFrame([
Row(abc=Row(xyz=Row(abc123="value123", services=[Row(type="type1", subtype="subtype1")])))
])
df.show(truncate=False)
# +---------------------------------+
# |abc |
# +---------------------------------+
# |{{value123, [{type1, subtype1}]}}|
# +---------------------------------+
from nestedfunctions.functions.hash import hash_field
hashed_df = hash_field(df, "abc.xyz.services.type", num_bits=256)
hashed_df.show(truncate=False)
# +--------------------------------------------------------------------------------------------+
# |abc |
# +--------------------------------------------------------------------------------------------+
# |{{value123, [{ba5857c2e8a7c12df14097eaa5ffb1c97976b9d433fe63a65df84849c5eea0ec, subtype1}]}}|
# +--------------------------------------------------------------------------------------------+