Find top N values for field X based on field Y's value

FrancoisCN · #1 (**permalink**) 05-29-2009

I want to find the top N entries for a certain field based on the values of another field.

For example if N=3, we want the 3 best values for each entry:

Entry1 ||| 100
Entry1 ||| 95
Entry1 ||| 30
Entry1 ||| 80
Entry1 ||| 50
Entry2 ||| 40
Entry2 ||| 20
Entry2 ||| 10
Entry2 ||| 50
Entry2 ||| 30

would return

Entry1 ||| 100
Entry1 ||| 95
Entry1 ||| 80
Entry2 ||| 40
Entry2 ||| 50
Entry2 ||| 30

ghostdog74 · #2 (**permalink**) 05-29-2009

if you have Python

Code:

d={}
for line in open("file"):
    line=line.strip().split(" ||| ")
    d.setdefault(line[0],[])
    d[line[0]].append(line[-1])
for i,j in d.iteritems():
    for item in sorted(j,lambda x,y: int(y)-int(x))[:3]:
        print "%s ||| %s" %(i,item)

output

Code:

# ./test.py
Entry2 ||| 50
Entry2 ||| 40
Entry2 ||| 30
Entry1 ||| 100
Entry1 ||| 95
Entry1 ||| 80

show your code next time.

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Bits Awarded / Charged to ghostdog74 for this Post
Date	User	Comment	Amount
05-29-2009	FrancoisCN	N/A	2,000

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