python given a list of dictionaries, calculate the rank of that dictionary using a specific field-CodePudding

given a list of dictionaries with all the same format and fields, calculate the rank of the dictionary based on a field. In the example below, I want to print the age ranking of each person

Ex:

dicts = [
    {
        'name': 'John',
        'age': 23
    },
    {
        'name': 'Sue',
        'age': 29
    },
    ...
]
for person in dicts:
    age_rank = ...
    print(f"{person['name']} is age-rank {age_rank}")

The oldest person should be rank 1, the next highest is rank 2, etc.

Edit: is there any way to keep the for loop untouched?

CodePudding user response：

Iterate over your values sorted by age descending, then combine with enumerate to generate the iteration index

for rank, person in enumerate(sorted(dicts, key=lambda x: x['age'], reverse=True), start=1):
    print(f"{person['name']} is age-rank {rank}")

CodePudding user response：

It depends on what you want to do after but maybe using Pandas could be a good choice:

import pandas as pd

df = pd.DataFrame(dicts)
df['age_rank'] = df['age'].rank(method='dense').astype(int)
print(df)

# Output
   name  age  age_rank
0  John   23         1
1   Sue   29         2

Update

I am wanting to keep the for loop in the exact format that I've described. i.e. keep for person in dicts untouched

for person in dicts:
    age_rank = sum(person['age'] < x['age'] for x in dicts)   1
    print(f"{person['name']} is age-rank {age_rank}")

# Output
John is age-rank 2
Sue is age-rank 1

CodePudding user response：

You can sort base age of each dict in list then print as you like with for-loop on result of sort:

dicts = [
    {
        'name': 'John',
        'age': 23
    },
    {
        'name': 'Sue',
        'age': 29
    },
]

for rnk , dct in enumerate(sorted(dicts, key=lambda x: x['age'], reverse=True)):
    print(f"{dct['name']} is age-rank {rnk 1}")

Update Without changing for-loop in the Question First sorting age, at the end use index for finding the rank from the sorting list.

srt_ages = sorted([dct['age'] for dct in dicts], reverse=True)
for person in dicts:
    age_rank = srt_ages.index(person['age']) 1
    print(f"{person['name']} is age-rank {age_rank}")

Sue is age-rank 1
John is age-rank 2