CODEWITHSUNDEEP
python
VICTOR
VICTOR

Reputation: 1942

Python sorting dictionary

I want to sort the following dictionary by the keys score, which is an array.

student = {"name" : [["Peter"], ["May"], ["Sharon"]],
           "score" : [[1,5,3], [3,2,6], [5,9,2]]}

For a better representation:

Peter ---- [1,5,3]
May ---- [3,2,6]
Sharon ---- [5,9,2]

Here I want to use the second element of score to sort the name into a list.

The expected result is:

name_list = ("May ", "Peter", "Sharon")

I have tried to use

sorted_x = sorted(student.items(), key=operator.itemgetter(1))

and

for x in sorted(student, key=lambda k: k['score'][1]):
    name_list.append(x['name'])

but both dont work.

Upvotes: 0

Views: 103

Answers (3)

Mehdi
Mehdi

Reputation: 679

If you want to use dictionaries, I suggest using OrderedDict:

name = ["Peter", "May", "Sharon"]
score = [[1,5,3], [3,2,6], [5,9,2]]
d = {n: s for (n, s) in zip(name, score)}

from collections import OrderedDict
ordered = OrderedDict(sorted(d.items(), key=lambda t: t[1][1]))
list(ordered)  # to retrieve the names

But, if not, the following would be a simpler approach:

name = ["Peter", "May", "Sharon"]
score = [[1,5,3], [3,2,6], [5,9,2]]
d = [(n, s) for (n, s) in zip(name, score)]

ordered = sorted(d, key=lambda t: t[1][1])
names_ordered = [item[0] for item in ordered]

Upvotes: 1

Matthias Fripp
Matthias Fripp

Reputation: 18645

This would probably work for you:

student = {
    "name": [["Peter"], ["May"], ["Sharon"]],
    "score": [[1,5,3], [3,2,6], [5,9,2]]
}

# pair up the names and scores
# this gives one tuple for each student:
# the first item is their name as a 1-item list
# the second item is their list of scores
pairs = zip(student['name'], student['score'])

# sort the tuples by the second score:
pairs_sorted = sorted(
    pairs,
    key=lambda t: t[1][1]
)

# get the names, in order
names = [n[0] for n, s in pairs_sorted]

print names
# ['May', 'Peter', 'Sharon']

Upvotes: 1

Joey.Chang
Joey.Chang

Reputation: 164

First zip the students name and score use zip.

zip(student["name"], student["score"])

you will get better representation:

[(['May'], [3, 2, 6]), 
 (['Peter'], [1, 5, 3]), 
 (['Sharon'], [5, 9, 2])]

then sort this list and get the student name:

In [10]: [ i[0][0] for i in sorted(zip(student["name"], student["score"]), key=lambda x: x[1][1])]
Out[10]: ['May', 'Peter', 'Sharon']

Know about the sorted buildin function first: https://docs.python.org/2/howto/sorting.html#sortinghowto

Upvotes: 3

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