How to get the index with the key in Python dictionary

Question

I have the key of a python dictionary and I want to get the corresponding index in the dictionary  Suppose I have the following dictionary   d      a   10   b   20   c   30    Is there a combination of python functions so that I can get the index value of 1  given the key value  b    d     b      I know it can be achieved with a loop or lambda  with a loop embedded   Just thought there should be a more straightforward way

User · Answer

Dictionaries in python have no order  You could use a list of tuples as your data structure instead   d      a   10   b   20   c   30  newd      a  10     b  20     c  30     Then this code could be used to find the locations of keys with a specific value  locations    i for i  t in enumerate newd  if t 0    b     gt  gt  gt   1

User · Answer

Creating dictionary animals     quot Cat quot     quot Pat quot    quot Dog quot     quot Pat quot    quot Tiger quot     quot Wild quot     Convert dictionary to list  array  keys   list animals    Printing 1st dictionary key by index print keys 0     Done

User · Answer

Use OrderedDicts  http   docs python org 2 library collections html collections OrderedDict   gt  gt  gt  x   OrderedDict    a    1      c    3      b    2      gt  gt  gt  x  d     4  gt  gt  gt  x keys   index  d   3  gt  gt  gt  x keys   index  c   1   For those using Python 3   gt  gt  gt  list x keys    index  c   1

User · Answer

No  there is no straightforward way because Python dictionaries do not have a set ordering   From the documentation      Keys and values are listed in an arbitrary order which is non-random  varies across Python implementations  and depends on the dictionary   s history of insertions and deletions    In other words  the  index  of b depends entirely on what was inserted into and deleted from the mapping before    gt  gt  gt  map     gt  gt  gt  map  b   1  gt  gt  gt  map   b   1   gt  gt  gt  map  a   1  gt  gt  gt  map   a   1   b   1   gt  gt  gt  map  c   1  gt  gt  gt  map   a   1   c   1   b   1    As of Python 2 7  you could use the collections OrderedDict   type instead  if insertion order is important to your application

[python] How to get the index with the key in Python dictionary?

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