将标签分配给PySpark中的表中的分类数据
问题描述:
我想使用pyspark sql将标签分配给下面的数据框中的分类数字。将标签分配给PySpark中的表中的分类数据
在婚姻栏1 =已婚,2 =未婚。在教育列1 =梯度和2 =本科生
Current Dataframe: +--------+---------+-----+ |MARRIAGE|EDUCATION|Total| +--------+---------+-----+ | 1| 2| 87| | 1| 1| 123| | 2| 2| 3| | 2| 1| 8| +--------+---------+-----+
Resulting Dataframe: +---------+---------+-----+ |MARRIAGE |EDUCATION|Total| +---------+---------+-----+ |Married |Grad | 87| |Married |UnderGrad| 123| |UnMarried|Grad | 3| |UnMarried|UnderGrad| 8| +---------+---------+-----+
是否有可能使用单个UDF和withColumn()来分配标签?有没有什么办法通过传递整个数据框并保持列名不变,从而在单个UDF中分配?
我可以想出一个解决方案,通过使用单独的udfs来完成每列的操作,如下所示。但无法弄清楚是否有办法一起做。
from pyspark.sql import functions as F
def assign_marital_names(record):
if record == 1:
return "Married"
elif record == 2:
return "UnMarried"
def assign_edu_names(record):
if record == 1:
return "Grad"
elif record == 2:
return "UnderGrad"
assign_marital_udf = F.udf(assign_marital_names)
assign_edu_udf = F.udf(assign_edu_names)
df.withColumn("MARRIAGE", assign_marital_udf("MARRIAGE")).\
withColumn("EDUCATION", assign_edu_udf("EDUCATION")).show(truncate=False)
答
一个UDF只能生成一列。但是这可以是结构化的专栏,并且UDF可以在婚姻和教育上应用标签。看到下面的代码:
from pyspark.sql.types import *
from pyspark.sql import Row
udf_result = StructType([StructField('MARRIAGE', StringType()), StructField('EDUCATION', StringType())])
marriage_dict = {1: 'Married', 2: 'UnMarried'}
education_dict = {1: 'Grad', 2: 'UnderGrad'}
def assign_labels(marriage, education):
return Row(marriage_dict[marriage], education_dict[education])
assign_labels_udf = F.udf(assign_labels, udf_result)
df.withColumn('labels', assign_labels_udf('MARRIAGE', 'EDUCATION')).printSchema()
root
|-- MARRIAGE: long (nullable = true)
|-- EDUCATION: long (nullable = true)
|-- Total: long (nullable = true)
|-- labels: struct (nullable = true)
| |-- MARRIAGE: string (nullable = true)
| |-- EDUCATION: string (nullable = true)
但是,正如你所看到的,它并不取代原来的列,它只是增加一个新的。要替换它们,您需要两次使用withColumn
,然后再使用labels
。