Getting the maximum value from filtered values in pandas DataFrames?

I want to Filter the days to Monday and get the maximum OverallGrade got on Mondays. Alternatively I have made a new Data frame for it and it shows the intended answer 90, but is there a way to do this without creating a new Data Frame?

When seeing the end result i need to see the student id also as shown in the alt solution! Also I do not want to use days as the index and reset the index again for this purpose! ( I actually have the days as dates and do not want to use them as the index, just converted to Day names here for simplicity)

import pandas as pd

ClassData = {
  "Days":         ["Monday","Wednesday","Monday","Friday","Tuesday","Monday","Friday"],
  "OverallMarks": [   150,     140,       180,      250,      200 ,    240,     170  ],
  "OverallGrade": [    70,      60,        90,      110,       85 ,     80,      71  ],
  "StudentID" :   ['a','b', 'c', 'd', 'e', 'f', 'g']
}

MyDataFrame1 = pd.DataFrame(ClassData)

# Alternate Solution I use - Creating a new Dataframe for only the mondays
NewDataFrame = MyDataFrame1[ MyDataFrame1['Days'] == "Monday" ] # Gets all Mondays
print( NewDataFrame[ NewDataFrame['OverallGrade'] == int(NewDataFrame['OverallGrade'].max()) ][['StudentID','OverallGrade']] ) 
# Gets max grade as 90 and shows the student id and grade

CodePudding user response：

First select on "Monday", just like you did
Then sort it descending, based on the 'OverallGrade'
Select the first element

print( MyDataFrame1[ MyDataFrame1['Days'] == "Monday" ].sort_values(by='OverallGrade', ascending=False).iloc[0])