How can I sort a dictionary by key

Question

What would be a nice way to go from  2 3  1 89  4 5  3 0  to  1 89  2 3  3 0  4 5   I checked some posts but they all use the  sorted  operator that returns tuples

User · Answer

There are a number of Python modules that provide dictionary implementations which automatically maintain the keys in sorted order. Consider the sortedcontainers module which is pure-Python and fast-as-C implementations. There is also a performance comparison with other popular options benchmarked against one another.

Using an ordered dict is an inadequate solution if you need to constantly add and remove key/value pairs while also iterating.

>>> from sortedcontainers import SortedDict
>>> d = {2:3, 1:89, 4:5, 3:0}
>>> s = SortedDict(d)
>>> s.items()
[(1, 89), (2, 3), (3, 0), (4, 5)]

The SortedDict type also supports indexed location lookups and deletion which isn't possible with the built-in dict type.

>>> s.iloc[-1]
4
>>> del s.iloc[2]
>>> s.keys()
SortedSet([1, 2, 4])

User · Answer

For the way how question is formulated  the most answers here are answering it correctly   However  considering how the things should be really done  taking to acount decades and decades of computer science  it comes to my total suprise that there is actually only one answer here  from GrantJ user  suggesting usage of sorted associative containers  sortedcontainers  which sorts elements based on key at their insertions point    That will avoid massive performance impact per each calling of sort       at minimum O N log N    where N is in number of elements  logically  this applies for all such solutions here which suggest to use the sort        Take to account that for all such solutions  the sort      will need to be called every time when  colletion needs to be accessed as sorted AFTER it was modified by adding removing elements

User · Answer

In Python 3     gt  gt  gt  D1    2 3  1 89  4 5  3 0   gt  gt  gt  for key in sorted D1       print  key  D1 key     gives  1 89 2 3 3 0 4 5

User · Answer

As others have mentioned  dictionaries are inherently unordered   However  if the issue is merely displaying dictionaries in an ordered fashion  you can override the   str   method in a dictionary subclass  and use this dictionary class rather than the builtin dict   Eg   class SortedDisplayDict dict      def   str   self          return            join   r   r     key  self key   for key in sorted self            gt  gt  gt  d   SortedDisplayDict  2 3  1 89  4 5  3 0    gt  gt  gt  d  1  89  2  3  3  0  4  5    Note  this changes nothing about how the keys are stored  the order they will come back when you iterate over them etc  just how they re displayed with print or at the python console

User · Answer

Standard Python dictionaries are unordered  Even if you sorted the  key value  pairs  you wouldn t be able to store them in a dict in a way that would preserve the ordering   The easiest way is to use OrderedDict  which remembers the order in which the elements have been inserted   In  1   import collections  In  2   d    2 3  1 89  4 5  3 0   In  3   od   collections OrderedDict sorted d items      In  4   od Out 4   OrderedDict   1  89    2  3    3  0    4  5      Never mind the way od is printed out  it ll work as expected   In  11   od 1  Out 11   89  In  12   od 3  Out 12   0  In  13   for k  v in od iteritems    print k  v           1 89 2 3 3 0 4 5   Python 3  For Python 3 users  one needs to use the  items   instead of  iteritems     In  13   for k  v in od items    print k  v            1 89 2 3 3 0 4 5

User · Answer

Guys you are making things complicated     it s really simple  from pprint import pprint Dict   B  1  A  2  C  3  pprint Dict    The output is     A  2  B  1  C  3

User · Answer

from operator import itemgetter   if you would like to play with multiple dictionaries then here you go    Three dictionaries that are composed of first name and last name  user           fname    Mo    lname    Mahjoub          fname    Abdo    lname    Al-hebashi          fname    Ali    lname    Muhammad        This loop will sort by the first and the last names    notice that in a dictionary order doesn t matter  So it could put the first name first or the last name first   for k in sorted  user  key itemgetter   fname    lname         print  k     This one will sort by the first name only  for x in sorted  user  key itemgetter   fname         print  x

User · Answer

Here I found some simplest solution to sort the python dict by key using pprint  eg     gt  gt  gt  x     a   10   cd   20   b   30   az   99    gt  gt  gt  print x   a   10   b   30   az   99   cd   20    but while using pprint it will return sorted dict   gt  gt  gt  import pprint   gt  gt  gt  pprint pprint x    a   10   az   99   b   30   cd   20

User · Answer

I come up with single line dict sorting     gt  gt  a    2 3  1 89  4 5  3 0   gt  gt  c    i a i  for i in sorted a keys      gt  gt  print c   1  89  2  3  3  0  4  5   Finished in 0 4s    Hope this will be helpful

User · Answer

Python dictionary was unordered before Python 3 6  In CPython implementation of Python 3 6  dictionary keeps the insertion order  From Python 3 7  this will become a language feature   In changelog of Python 3 6  https   docs python org 3 6 whatsnew 3 6 html whatsnew36-compactdict       The order-preserving aspect of this new implementation is considered   an implementation detail and should not be relied upon  this may   change in the future  but it is desired to have this new dict   implementation in the language for a few releases before changing the   language spec to mandate order-preserving semantics for all current   and future Python implementations  this also helps preserve   backwards-compatibility with older versions of the language where   random iteration order is still in effect  e g  Python 3 5     In document of Python 3 7  https   docs python org 3 7 tutorial datastructures html dictionaries       Performing list d  on a dictionary returns a list of all the keys used   in the dictionary  in insertion order  if you want it sorted  just use   sorted d  instead     So unlike previous versions  you can sort a dict after Python 3 6 3 7  If you want to sort a nested dict including the sub-dict inside  you can do   test dict     a   1   c   3   b     b2   2   b1   1    def dict reorder item       return  k  sort dict v  if isinstance v  dict  else v for k  v in sorted item items      reordered dict   dict reorder test dict    https   gist github com ligyxy f60f0374defc383aa098d44cfbd318eb

User · Answer

There is an easy way to sort a dictionary   According to your question   The solution is    c  2 3  1 89  4 5  3 0  y sorted c items    print y    Where c is the name of your dictionary    This program gives the following output     1  89    2  3    3  0    4  5     like u wanted   Another example is   d   John  36  Lucy  24  Albert  32  Peter  18  Bill  41  x sorted d keys    print x   Gives the output   Albert    Bill    John    Lucy    Peter    y sorted d values    print y   Gives the output  18  24  32  36  41   z sorted d items    print z   Gives the output      Albert   32     Bill   41     John   36     Lucy   24     Peter   18     Hence by changing it into keys  values and items   you can print like what u wanted Hope this helps

User · Answer

A timing comparison of the two methods in 2 7 shows them to be virtually identical    gt  gt  gt  setup string    a   sorted dict  2 3  1 89  4 5  3 0   items      gt  gt  gt  timeit timeit stmt    k  val  for k  val in a    setup setup string  number 10000  0 003599141953657181   gt  gt  gt  setup string    from collections import OrderedDict n   gt  gt  gt  setup string     a   OrderedDict  1 89  2 3  3 0  4 5   n   gt  gt  gt  setup string     b   a items     gt  gt  gt  timeit timeit stmt    k  val  for k  val in b    setup setup string  number 10000  0 003581275490432745

User · Answer

Simply   d    2 3  1 89  4 5  3 0  sd   sorted d items     for k v in sd      print k  v   Output   1 89 2 3 3 0 4 5

User · Answer

Dictionaries themselves do not have ordered items as such  should you want to print them etc to some order  here are some examples   In Python 2 4 and above   mydict     carl  40             alan  2             bob  1             danny  3   for key in sorted mydict       print   s   s     key  mydict key     gives   alan  2 bob  1 carl  40 danny  3    Python below 2 4    keylist   mydict keys   keylist sort   for key in keylist      print   s   s     key  mydict key     Source  http   www saltycrane com blog 2007 09 how-to-sort-python-dictionary-by-keys

User · Answer

Python dicts are un-ordered  Usually  this is not a problem since the most common use case is to do a lookup    The simplest way to do what you want would be to create a collections OrderedDict inserting the elements in sorted order   ordered dict   collections OrderedDict   k  d k   for k in sorted d keys        If you need to iterated  as others above have suggested  the simplest way would be to iterate over sorted keys  Examples-  Print values sorted by keys     create the dict d    k1 v1  k2 v2        iterate by keys in sorted order for k in sorted d keys         value   d k        do something with k  value like print     print k  value   Get list of values sorted by keys   values    d k  for k in sorted d keys

User · Answer

I think the easiest thing is to sort the dict by key and save the sorted key value pair in a new dict   dict1     renault   3   ford  4   volvo   1   toyota   2   dict2                         create an empty dict to store the sorted values for key in sorted dict1 keys         if not key in dict2       Depending on the goal  this line may not be neccessary         dict2 key    dict1 key    To make it clearer   dict1     renault   3   ford  4   volvo   1   toyota   2   dict2                         create an empty dict to store the sorted     values for key in sorted dict1 keys         if not key in dict2       Depending on the goal  this line may not be  neccessary         value   dict1 key          dict2 key    value

User · Answer

dictionary    1  2  2    5  4 5  4  5  3  1    temp sorted dictionary  sorted dict   dict   k dictionary k   for i k in enumerate temp     sorted dict            1   2   2      3   1   4   5   5   4  5

User · Answer

Found another way   import json print json dumps d  sort keys   True    upd  1  this also sorts nested objects  thanks  DanielF   2  python dictionaries are unordered therefore this is sutable for print or assign to str only

User · Answer

Or use pandas  Demo   gt  gt  gt  d   B  1  A  2  C  3   gt  gt  gt  df pd DataFrame d index  0   sort index axis 1     A  B  C 0  2  1  3  gt  gt  gt  df to dict  int   0    A   2   B   1   C   3   gt  gt  gt    See   Docs of this Documentation of whole pandas

User · Answer

From Python s collections library documentation    gt  gt  gt  from collections import OrderedDict   gt  gt  gt    regular unsorted dictionary  gt  gt  gt  d     banana   3   apple  4   pear   1   orange   2    gt  gt  gt    dictionary sorted by key -- OrderedDict sorted d items    also works  gt  gt  gt  OrderedDict sorted d items    key lambda t  t 0    OrderedDict    apple   4     banana   3     orange   2     pear   1      gt  gt  gt    dictionary sorted by value  gt  gt  gt  OrderedDict sorted d items    key lambda t  t 1    OrderedDict    pear   1     orange   2     banana   3     apple   4      gt  gt  gt    dictionary sorted by length of the key string  gt  gt  gt  OrderedDict sorted d items    key lambda t  len t 0     OrderedDict    pear   1     apple   4     orange   2     banana   3

User · Answer

An easy way to do this   d    2 3  1 89  4 5  3 0   s    k   d k  for k in sorted d    s   Out 1    1  89  2  3  3  0  4  5

User · Answer

My suggestion is this as it allows you to sort a dict or keep a dict sorted as you are adding items and might need to add items in the future   Build a dict from scratch as you go along   Have a second data structure  a list  with your list of keys   The bisect package has an insort function which allows inserting into a sorted list  or sort your list after completely populating your dict   Now  when you iterate over your dict  you instead iterate over the list to access each key in an in-order fashion without worrying about the representation of the dict structure  which was not made for sorting

User · Answer

Will generate exactly what you want     D1    2 3  1 89  4 5  3 0    sort dic        for i in sorted D1        sort dic update  i D1 i     print sort dic    1  89  2  3  3  0  4  5    But this is not the correct way to do this  because  It could show a distinct behavior with different dictionaries  which I have learned recently  Hence perfect way has been suggested by Tim In the response of my Query which I am sharing here   from collections import OrderedDict sorted dict   OrderedDict sorted D1 items    key lambda t  t 0

User · Answer

For CPython PyPy 3 6  and any Python 3 7 or higher  this is easily done with    gt  gt  gt  d    2 3  1 89  4 5  3 0   gt  gt  gt  dict sorted d items      1  89  2  3  3  0  4  5

User · Answer

This function will sort any dictionary recursively by its key  That is  if any value in the dictionary is also a dictionary  it too will be sorted by its key  If you are running on CPython 3 6 or greater  than a simple change to use a dict rather than an OrderedDict can be made   from collections import OrderedDict  def sort dict d       items     k  v  for k  v in sorted d items    key lambda x  x 0        for item in items          if isinstance item 1   dict               item 1    sort dict item 1       return OrderedDict items       return dict items

User · Answer

l   dict keys   l2   l l2 append 0  l3      for repeater in range 0  len l        smallnum   float  inf       for listitem in l2          if listitem  lt  smallnum              smallnum   listitem     l2 remove smallnum      l3 append smallnum  l3 remove 0  l   l3  for listitem in l      print listitem

User · Answer

Simplest solution is that you should get a list of dict key is sorted order and then iterate over dict  For example  a1     a  1   b  13   d  4   c  2   e  30  a1 sorted keys   sorted a1  key a1 get  reverse True  for r in a1 sorted keys      print r  a1 r    Following will be the output  desending order   e 30 b 13 d 4 c 2 a 1

User · Answer

You can create a new dictionary by sorting the current dictionary by key as per your question   This is your dictionary  d    2 3  1 89  4 5  3 0    Create a new dictionary d1 by sorting this d using lambda function  d1   dict sorted d items    key   lambda x x 0      d1 should be  1  89  2  3  3  0  4  5   sorted based on keys in d

[python] How can I sort a dictionary by key?

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