How to find maximum value of a column in python dataframe

问题

I have a data frame in pyspark. In this data frame I have column called id that is unique.

Now I want to find the maximum value of the column id in the data frame.

I have tried like below

df['id'].max()

But got below error

TypeError: 'Column' object is not callable

Please let me know how to find the maximum value of a column in data frame

In the answer by @Dadep the link gives the correct answer

回答1:

if you are using pandas .max() will work :

>>> df2=pd.DataFrame({'A':[1,5,0], 'B':[3, 5, 6]})
>>> df2['A'].max()
5

Else if it's a spark dataframe:

Best way to get the max value in a Spark dataframe column

回答2:

I'm coming from scala, but I do believe that this is also applicable on python.

val max = df.select(max("id")).first()

but you have first import the following :

from pyspark.sql.functions import max

回答3:

The following can be used in pyspark:

df.select(max("id")).show()

回答4:

You can use the aggregate max as also mentioned in the pyspark documentation link below:

Link : https://spark.apache.org/docs/latest/api/python/pyspark.sql.html?highlight=agg

Code:

row1 = df1.agg({"id": "max"}).collect()[0]

来源：https://stackoverflow.com/questions/43924686/how-to-find-maximum-value-of-a-column-in-python-dataframe