How to keep keys values in same order as declared

Question

I have a dictionary that I declared in a particular order and want to keep it in that order all the time  The keys values can t really be kept in order based on their value  I just want it in the order that I declared it   So if I have the dictionary   d     ac   33   gw   20   ap   102   za   321   bs   10    It isn t in that order if I view it or iterate through it  is there any way to make sure Python will keep the explicit order that I declared the keys values in

User · Answer

Another alternative is to use Pandas dataframe as it guarantees the order and the index locations of the items in a dict-like structure

User · Answer

from collections import OrderedDict OrderedDict  word  True  for word in words    contains   OrderedDict    He   True     will   True     be   True     the   True     winner   True      If the values are True  or any other immutable object   you can also use   OrderedDict fromkeys words  True

User · Answer

I had a similar problem when developing a Django project  I couldn t use OrderedDict  because I was running an old version of python  so the solution was to use Django s SortedDict class   https   code djangoproject com wiki SortedDict  e g    from django utils datastructures import SortedDict d2   SortedDict   d2  b     1 d2  a     2 d2  c     3   Note  This answer is originally from 2011  If you have access to Python version 2 7 or higher  then you should have access to the now standard collections OrderedDict  of which many examples have been provided by others in this thread

User · Answer

From Python 3 6 onwards  the standard dict type maintains insertion order by default  Defining d     ac  33   gw  20   ap  102   za  321   bs  10   will result in a dictionary with the keys in the order listed in the source code  This was achieved by using a simple array with integers for the sparse hash table  where those integers index into another array that stores the key-value pairs  plus the calculated hash   That latter array just happens to store the items in insertion order  and the whole combination actually uses less memory than the implementation used in Python 3 5 and before  See the original idea post by Raymond Hettinger for details  In 3 6 this  was still considered an implementation detail  see the What s New in Python 3 6 documentation   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    Python 3 7 elevates this implementation detail to a language specification  so  it is now mandatory that dict preserves order in all Python implementations compatible with that version or newer  See the pronouncement by the BDFL  As of Python 3 8  dictionaries also support iteration in reverse  You may still want to use the collections OrderedDict   class in certain cases  as it offers some additional functionality on top of the standard dict type  Such as as being reversible  this extends to the view objects   and supporting reordering  via the move to end   method

User · Answer

Generally  you can design a class that behaves like a dictionary  mainly be implementing the methods   contains      getitem      delitem      setitem   and some more   That class can have any behaviour you like  for example prividing a sorted iterator over the keys

User · Answer

Note that this answer applies to python versions prior to python3 7   CPython 3 6 maintains insertion order under most circumstances as an implementation detail   Starting from Python3 7 onward  it has been declared that implementations MUST maintain insertion order to be compliant     python dictionaries are unordered   If you want an ordered dictionary  try collections OrderedDict   Note that OrderedDict was introduced into the standard library in python 2 7   If you have an older version of python  you can find recipes for ordered dictionaries on ActiveState

User · Answer

Dictionaries will use an order that makes searching efficient  and you cant change that   You could just use a list of objects  a 2 element tuple in a simple case  or even a class   and append items to the end  You can then use linear search to find items in it   Alternatively you could create or use a different data structure created with the intention of maintaining order

User · Answer

You can t really do what you want with a dictionary  You already have the dictionary d     ac  33   gw  20   ap  102   za  321   bs  10 created  I found there was no way to keep in order once it is already created  What I did was make a json file instead with the object     ac  33  gw  20  ap  102  za  321  bs  10    I used   r   json load open  file json    object pairs hook OrderedDict    then used   print json dumps r    to verify

User · Answer

if you would like to have a dictionary  in a specific order  you can also create a list of lists  where the first item will be the key  and the second item will be the value and will look like this example    gt  gt  gt  list    1 2   2 3    gt  gt  gt  for i in list          print i 0          print i 1   1 2 2 3

User · Answer

Rather than explaining the theoretical part  I ll give a simple example    gt  gt  gt  from collections import OrderedDict  gt  gt  gt  my dictionary OrderedDict    gt  gt  gt  my dictionary  foo   3  gt  gt  gt  my dictionary  aol   1  gt  gt  gt  my dictionary OrderedDict    foo   3     aol   1     gt  gt  gt  dict my dictionary    foo   3   aol   1

User · Answer

You can do the same thing which i did for dictionary   Create a list and empty dictionary   dictionary items      fields      Name    Himanshu Kanojiya      email id    hima gmail com    l   fields 0  0  m   fields 0  1  n   fields 1  0  q   fields 1  1  dictionary items l    m dictionary items n    q print dictionary items

User · Answer

I came across this post while trying to figure out how to get OrderedDict to work  PyDev for Eclipse couldn t find OrderedDict at all  so I ended up deciding to make a tuple of my dictionary s key values as I would like them to be ordered  When I needed to output my list  I just iterated through the tuple s values and plugged the iterated  key  from the tuple into the dictionary to retrieve my values in the order I needed them   example   test dict   dict  val1    hi   val2    bye   val3    huh    val4    what       test tuple      val1    val2    val3    val4   for key in test tuple  print test dict key     It s a tad cumbersome  but I m pressed for time and it s the workaround I came up with   note  the list of lists approach that somebody else suggested does not really make sense to me  because lists are ordered and indexed  and are also a different structure than dictionaries

User · Answer

from collections import OrderedDict list1     k1    k2   list2     v1    v2   new ordered dict   OrderedDict zip list1  list2   print new ordered dict   OrderedDict    k1    v1      k2    v2

[python] How to keep keys/values in same order as declared?

Examples related to python

Examples related to sorting

Examples related to dictionary