用字典键值(pyspark)替换spark df中一列的值 [英] replace values of one column in a spark df by dictionary key-values (pyspark)

问题描述

我在pyspark中陷入了数据转换任务. 我想用字典中指定的键值对替换df中一列的所有值.

I got stucked with a data transformation task in pyspark. I want to replace all values of one column in a df with key-value-pairs specified in a dictionary.

dict = {'A':1, 'B':2, 'C':3}

我的df看起来像这样:

My df looks like this:

+-----------++-----------+
|       col1||       col2|
+-----------++-----------+
|          B||          A|
|          A||          A|
|          A||          A|
|          C||          B|
|          A||          A|
+-----------++-----------+

现在，我想用dict中定义的键值对替换col1的所有值.

Now I want to replace all values of col1 by the key-values pairs defined in dict.

所需的输出:

+-----------++-----------+
|       col1||       col2|
+-----------++-----------+
|          2||          A|
|          1||          A|
|          1||          A|
|          3||          B|
|          1||          A|
+-----------++-----------+

我尝试了

df.na.replace(dict, 1).show()

但是这也会替换col2上的值，该值将保持不变.

but that also replaces the values on col2, which shall stay untouched.

感谢您的帮助. 问候:)

Thank you for your help. Greetings :)

推荐答案

您的数据:

print df
DataFrame[col1: string, col2: string]
df.show()   
+----+----+
|col1|col2|
+----+----+
|   B|   A|
|   A|   A|
|   A|   A|
|   C|   B|
|   A|   A|
+----+----+

diz = {"A":1, "B":2, "C":3}

将字典的值从整数转换为字符串，以免出现替换不同类型的错误:

Convert values of your dictionary from integer to string, in order to not get errors of replacing different types:

diz = {k:str(v) for k,v in zip(diz.keys(),diz.values())}

print diz
{'A': '1', 'C': '3', 'B': '2'}

替换col1的值

df2 = df.na.replace(diz,1,"col1")
print df2
DataFrame[col1: string, col2: string]

df2.show()
+----+----+
|col1|col2|
+----+----+
|   2|   A|
|   1|   A|
|   1|   A|
|   3|   B|
|   1|   A|
+----+----+

如果您需要将值从String强制转换为Integer

If you need to cast your values from String to Integer

from pyspark.sql.types import *

df3 = df2.select(df2["col1"].cast(IntegerType()),df2["col2"]) 
print df3
DataFrame[col1: int, col2: string]

df3.show()
+----+----+
|col1|col2|
+----+----+
|   2|   A|
|   1|   A|
|   1|   A| 
|   3|   B|
|   1|   A|
+----+----+

这篇关于用字典键值(pyspark)替换spark df中一列的值的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！