Change the name of a key in dictionary

Question

I want to change the key of an entry in a Python dictionary   Is there a straightforward way to do this

User · Answer

You can associate the same value with many keys, or just remove a key and re-add a new key with the same value.

For example, if you have keys->values:

red->1
blue->2
green->4

there's no reason you can't add purple->2 or remove red->1 and add orange->1

User · Answer

Since keys are what dictionaries use to lookup values  you can t really change them  The closest thing you can do is to save the value associated with the old key  delete it  then add a new entry with the replacement key and the saved value  Several of the other answers illustrate different ways this can be accomplished

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Method if anyone wants to replace all occurrences of the key in a multi-level dictionary  Function checks if the dictionary has a specific key and then iterates over sub-dictionaries and invokes the function recursively  def update keys old key new key d       if isinstance d dict           if old key in d              d new key    d old key              del d old key          for key in d              updateKey old key new key d key    update keys  old   new  dictionary

User · Answer

No direct way to do this  but you can delete-then-assign  d    1 2 3 4   d newKey    d 1  del d 1    or do mass key changes   d   dict  changeKey k   v  for k  v in d items

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To convert all the keys in the dictionary  Suppose this is your dictionary    gt  gt  gt  sample     person-id    3    person-name    Bob     To convert all the dashes to underscores in the sample dictionary key    gt  gt  gt  sample    key replace  -         sample pop key  for key in sample keys     gt  gt  gt  sample  gt  gt  gt    person id    3    person name    Bob

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If you have a complex dict  it means there is a dict or list within the dict   myDict    1  one  2  3  three  4  four    myDict 2  5    myDict 2  pop 4  print myDict  Output  1   one   2   3   three   5   four

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I haven t seen this exact answer   dict  key     value   You can even do this to object attributes   Make them into a dictionary by doing this   dict   vars obj    Then you can manipulate the object attributes like you would a dictionary   dict  attribute     value

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I wrote this function below where you can change the name of a current key name to a new one   def change dictionary key name dict object  old name  new name                PARAMETERS            dict object  dict   The object of the dictionary to perform the change         old name  string   The original name of the key to be changed         new name  string   The new name of the key      RETURNS           final obj  The dictionary with the updated key names     Take the dictionary and convert its keys to a list      Update the list with the new value and then convert the list of the new keys to      a new dictionary             keys list   list dict object keys        for i in range len keys list            if  keys list i     old name               keys list i    new name      final obj   dict zip keys list  list dict object values           return final obj  Assuming a JSON you can call it and rename it by the following line  data   json load json file  for item in data      item   change dictionary key name item  old key name  new key name   Conversion from list to dictionary keys has been found here   https   www geeksforgeeks org python-ways-to-change-keys-in-dictionary

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Be aware of the position of pop  Put the key you want to delete after pop   orig dict  AAAAA     orig dict pop  A   orig dict     A   1   B    5    C    10   D    15       printing initial  print   quot original   quot   orig dict      changing keys of dictionary  orig dict  AAAAA     orig dict pop  A        printing final result  print   quot Changed   quot   str orig dict

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In python 2 7 and higher  you can use dictionary comprehension  This is an example I encountered while reading a CSV using a DictReader  The user had suffixed all the column names with      ori dict     key1     1   key2     2   key3     3   to get rid of the trailing     in the keys   corrected dict     k replace           v for k  v in ori dict items

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This will lowercase all your dict keys  Even if you have nested dict or lists  You can do something similar to apply other transformations  def lowercase keys obj     if isinstance obj  dict       obj    key lower    value for key  value in obj items        for key  value in obj items                   if isinstance value  list           for idx  item in enumerate value             value idx    lowercase keys item        obj key    lowercase keys value    return obj   json str     quot FOO quot    quot BAR quot    quot BAR quot   123   quot EMB LIST quot      quot FOO quot    quot bar quot    quot Bar quot   123     quot FOO quot    quot bar quot    quot Bar quot   123     quot EMB DICT quot     quot FOO quot    quot BAR quot    quot BAR quot   123   quot EMB LIST quot      quot FOO quot    quot bar quot    quot Bar quot   123     quot FOO quot    quot bar quot    quot Bar quot   123      lowercase keys json str    Out 0     foo    BAR     bar   123    emb list      foo    bar    bar   123     foo    bar    bar   123      emb dict     foo    BAR      bar   123     emb list      foo    bar    bar   123     foo    bar    bar   123

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An example of complete solution Declare a json file which contains mapping you want      quot old key name quot    quot new key name quot      quot old key name 2 quot    quot new key name 2 quot      Load it with open  quot  lt filepath gt  quot   as json file      format dict   json load json file   Create this function to format a dict with your mapping def format output dict to format format dict     for row in dict to format      if row in format dict keys   and row    format dict row         dict to format format dict row     dict to format pop row    return dict to format

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pop n fresh   gt  gt  gt a    1 2  3 4   gt  gt  gt a 5    a pop 1   gt  gt  gt a  3  4  5  2   gt  gt  gt

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d    1 2 3 4    suppose that we want to change the keys to the list elements p   a     b    the following code will do   d dict zip p list d values         and we get    a   2   b   4

User · Answer

Easily done in 2 steps   dictionary new key    dictionary old key  del dictionary old key    Or in 1 step   dictionary new key    dictionary pop old key    which will raise KeyError if dictionary old key  is undefined  Note that this will delete dictionary old key     gt  gt  gt  dictionary     1   one   2  two   3  three     gt  gt  gt  dictionary  ONE     dictionary pop 1   gt  gt  gt  dictionary  2   two   3   three    ONE    one    gt  gt  gt  dictionary  ONE     dictionary pop 1  Traceback  most recent call last     File   lt input gt    line 1  in  lt module gt  KeyError  1

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In case of changing all the keys at once  Here I am stemming the keys   a     making    1   jumping    2   climbing    1   running    2  b    ps stem w    a w  for w in a keys    print b   gt  gt  gt    climb   1   jump   2   make   1   run   2   output

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this function gets a dict  and another dict specifying how to rename keys  it returns a new dict  with renamed keys  def rekey inp dict  keys replace       return  keys replace get k  k   v for k  v in inp dict items     test  def test rekey        assert rekey   a   1   quot b quot   2   quot c quot   3     quot b quot    quot beta quot         a   1   quot beta quot   2   quot c quot   3

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if you want to change all the keys   d     x  1   y  2   z  3  d1     x   a    y   b    z   c    In  10   dict  d1 key   value  for  key  value  in d items    Out 10     a   1   b   2   c   3    if you want to change single key     You can go with any of the above suggestion

[python] Change the name of a key in dictionary

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