
        
        
            
                
                
                    df = spark.createDataFrame([["Alex", 25], ["Bob", 30]], ["name", "age"])
df.show()
                
            
            +----+---+
|name|age|
+----+---+
|Alex| 25|
| Bob| 30|
+----+---+

Getting the maximum value of a PySpark column

To obtain the maximum age:


        
        
            
                
                
                    import pyspark.sql.functions as F
df.select(F.max("age")).show()
                
            
            +--------+
|max(age)|
+--------+
|      30|
+--------+

To obtain the maximum age as an integer:


        
        
            
                
                
                    list_rows = df.select(F.max("age")).collect()
list_rows[0][0]
                
            
            30

Here, the collect() method returns a list of Row objects, which in this case is length one because the PySpark DataFrame returned by select(~) only has one row. The content of the Row object can be accessed via [0].

Getting the maximum value of each group in PySpark

Consider the following PySpark DataFrame:


        
        
            
                
                
                    df = spark.createDataFrame([["Alex", 20, "A"],\
                            ["Bob", 30, "B"],\
                            ["Cathy", 50, "A"]],
                            ["name", "age", "class"])
df.show()
                
            
            +-----+---+-----+
| name|age|class|
+-----+---+-----+
| Alex| 20|    A|
|  Bob| 30|    B|
|Cathy| 50|    A|
+-----+---+-----+

To get the maximum age of each class:


        
        
            
                
                
                    df.groupby("class").agg(F.max("age").alias("MAX AGE")).show()
                
            
            +-----+-------+
|class|MAX AGE|
+-----+-------+
|    A|     50|
|    B|     30|
+-----+-------+

Here, we are using the alias(~) method to assign a label to the aggregated age column.

Published by Isshin Inada

Edited by 0 others

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Official PySpark Documentation

https://spark.apache.org/docs/latest/api/python/reference/api/pyspark.sql.functions.max.html

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