Get user position between users-CodePudding

I have a database of users with marks.

I want to loop into marks and get user positions. Let's say user1 marks are higher, the position would 1 and so on.

The output would be something like this:

user1 5121 1
user2 500  2
user3 400  3

I tried with:

sorted(range(len(user[marks])), key=lambda i: a[i], reverse=True)

But this only print out the highest to lowest.

My database model:

class user(db.Model):        
    id = db.Column(Integer, primary_key=True, autoincrement=True)
    name = db.Column(String(250), nullable=False)
    marks = db.Column(Integer, nullable=False)
    position = db.Column(Integer, nullable=False)

CodePudding user response：

If you can get you data in Pandas DataFrame then you can do something like this:

import pandas as pd

df = pd.DataFrame({
    "user": ['user1', 'user2', 'user3'],
    "marks": [5121, 400, 500]
})

# Sort dataframe by marks, and use index as rank
df.sort_values(['marks'], ascending=False, ignore_index=True)

CodePudding user response：

I think you mean you want to find the rank. Try this:

import pandas as pd
df = pd.DataFrame({
    "user": ['user1', 'user2', 'user3'],
    "marks": [5121, 400, 500]
})

df['rank'] = df['marks'].rank(method='dense', ascending=False).astype(int)

df = df.sort_values('rank', ignore_index=True)

Your output would look like this:


     user  marks  rank
0   user1   5121     1
1   user3    500     2
2   user2    400     3

ignore_index=True would reindex based on rank as well

CodePudding user response：

You already achieved the sorted list of marks, highest to lowest, let's call it ranks. Just enumerate it and add 1.

[(i 1,e) for i,e in enumerate(ranks)]

Not sure why pandas is needed. Provide exact fields and formats for more detail.