How to Sort a Dictionary by Value

How do I sort a dictionary by value?

Python 3.7+ or CPython 3.6

Dicts preserve insertion order in Python 3.7+. Same in CPython 3.6, but it's an implementation detail.

>>> x = {1: 2, 3: 4, 4: 3, 2: 1, 0: 0}
>>> {k: v for k, v in sorted(x.items(), key=lambda item: item[1])}
{0: 0, 2: 1, 1: 2, 4: 3, 3: 4}

or

>>> dict(sorted(x.items(), key=lambda item: item[1]))
{0: 0, 2: 1, 1: 2, 4: 3, 3: 4}

Older Python

It is not possible to sort a dictionary, only to get a representation of a dictionary that is sorted. Dictionaries are inherently orderless, but other types, such as lists and tuples, are not. So you need an ordered data type to represent sorted values, which will be a list—probably a list of tuples.

For instance,

import operator
x = {1: 2, 3: 4, 4: 3, 2: 1, 0: 0}
sorted_x = sorted(x.items(), key=operator.itemgetter(1))

sorted_x will be a list of tuples sorted by the second element in each tuple. dict(sorted_x) == x.

And for those wishing to sort on keys instead of values:

import operator
x = {1: 2, 3: 4, 4: 3, 2: 1, 0: 0}
sorted_x = sorted(x.items(), key=operator.itemgetter(0))

In Python3 since unpacking is not allowed we can use

x = {1: 2, 3: 4, 4: 3, 2: 1, 0: 0}
sorted_x = sorted(x.items(), key=lambda kv: kv[1])

If you want the output as a dict, you can use collections.OrderedDict:

import collections

sorted_dict = collections.OrderedDict(sorted_x)

How do you sort a dictionary by value?

Use:

using System.Linq.Enumerable;
...
List<KeyValuePair<string, string>> myList = aDictionary.ToList();

myList.Sort(
    delegate(KeyValuePair<string, string> pair1,
    KeyValuePair<string, string> pair2)
    {
        return pair1.Value.CompareTo(pair2.Value);
    }
);

Since you're targeting .NET 2.0 or above, you can simplify this into lambda syntax -- it's equivalent, but shorter. If you're targeting .NET 2.0 you can only use this syntax if you're using the compiler from Visual Studio 2008 (or above).

var myList = aDictionary.ToList();

myList.Sort((pair1,pair2) => pair1.Value.CompareTo(pair2.Value));

How do I sort a list of dictionaries by a value of the dictionary?

The sorted() function takes a key= parameter

newlist = sorted(list_to_be_sorted, key=lambda d: d['name']) 

Alternatively, you can use operator.itemgetter instead of defining the function yourself

from operator import itemgetter
newlist = sorted(list_to_be_sorted, key=itemgetter('name')) 

For completeness, add reverse=True to sort in descending order

newlist = sorted(list_to_be_sorted, key=itemgetter('name'), reverse=True)

Sort Dict by Values in Python 3.6+

By default, the dictionary is sorted based on keys, but the sorted function takes a function as a parameter using which you can alter the behaviour for
program.

d={'a':6,'b':4,'k':3}
print(sorted(d)) 

sorted_by_values= sorted(d,key=lambda x:d[x])
print(sorted_by_values)

Python sort dictionary based on value inside a list

>>> dict(sorted(x.items(), key=lambda item: item[1][0]))

out:

{'Beat': [18, '100% to work', '10%'], 'Nikolas': [25, '29% to work', '94%'], 'George': [68, '0% to work', '70%']}

How to sort dictionary based on values and if multiple keys have same values then sort by keys

For your dict, you can simply sort with key=lambda x: (x[1], x[0])

For your code, you can also use a Counter from collection module, like this:

freq = Counter(a)

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