5 maximum values in a python dictionary
PythonDictionaryMaxPython Problem Overview
I have a dictionary like this:
A = {'a':10, 'b':843, 'c': 39,.....}
I want to get the 5 maximum values of this dict and store a new dict with this. To get the maximum value I did:
max(A.iteritems(), key=operator.itemgetter(1))[0:]
Perhaps it is an easy task, but I am stuck on it for a long time. Please help!!!
Python Solutions
Solution 1 - Python
No need to use iteritems and itemgetter. The dict's own get method works fine.
max(A, key=A.get)
Similarly for sorting:
sorted(A, key=A.get, reverse=True)[:5]
Finally, if the dict size is unbounded, using a heap will eventually be faster than a full sort.
import heapq
heapq.nlargest(5, A, key=A.get)
For more information, have a look at the heapq documentation.
Solution 2 - Python
You are close. You can sort the list using sorted [docs] and take the first five elements:
newA = dict(sorted(A.iteritems(), key=operator.itemgetter(1), reverse=True)[:5])
See also: Python Sorting HowTo
Solution 3 - Python
You could use collections.Counter here:
dict(Counter(A).most_common(5))
Example:
>>> from collections import Counter
>>> A = {'a' : 1, 'b' : 3, 'c' : 2, 'd' : 4, 'e' : 0, 'f' :5}
>>> dict(Counter(A).most_common(5))
{'a': 1, 'c': 2, 'b': 3, 'd': 4, 'f': 5}
Solution 4 - Python
For Python 3
import operator
dict(sorted(A.items(), key=operator.itemgetter(1), reverse=True)[:5])
Solution 5 - Python
Try this:
dict(sorted(A.iteritems(), key=operator.itemgetter(1), reverse=True)[:5])