Why does this python dictionary get created out of order using setdefault()?

by

Dictionaries have no order in python. In other words, when you iterate over a dictionary, the order that the keys/items are “yielded” is not the order that you put them into the dictionary. (Try your code on a different version of python and you’re likely to get differently ordered output). If you want a dictionary that is ordered, you need a collections.OrderedDict which wasn’t introduced until python 2.7. You can find equivalent recipes on ActiveState if you’re using an older version of python. However, often it’s good enough to just sort the items (e.g. sorted(mydict.items()).

EDIT as requested, an OrderedDict example:

from collections import OrderedDict
groupL = OrderedDict()  # groupL for Loop
c = 0
for n in range(0,13):
    c += 1
    l = chr(n+97)
    groupL.setdefault(l,c)

print (groupL)

More Related Contents:

  1. Use cases for the ‘setdefault’ dict method
  2. Creating a list of dictionaries with same keys? [duplicate]
  3. How to change all the dictionary keys in a for loop with d.items()?
  4. What am i doing wrong in this python script?
  5. How can I remove a key from a Python dictionary?
  6. Reverse / invert a dictionary mapping
  7. Convert list of dictionaries to a pandas DataFrame
  8. Are list-comprehensions and functional functions faster than “for loops”?
  9. How do I initialize a dictionary of empty lists in Python?
  10. How to return dictionary keys as a list in Python?
  11. Dictionary: Get list of values for list of keys
  12. In Python, when to use a Dictionary, List or Set?
  13. Create a list with initial capacity in Python
  14. How do you create nested dict in Python?
  15. Inverting a dictionary with list values
  16. How to change index of a for loop?
  17. How to get the difference between two dictionaries in Python?
  18. Is there a clever way to pass the key to defaultdict’s default_factory?
  19. How to print a dictionary’s key?
  20. What is the right way to treat Python argparse.Namespace() as a dictionary?
  21. How to print a dictionary line by line in Python?
  22. Sorting a dictionary with lists as values, according to an element from the list
  23. How to create a dictionary from a line of text?
  24. Convert list of strings to dictionary
  25. Return first N key:value pairs from dict
  26. Why do I get an error “‘unicode’ object does not support item deletion” when trying to delete values from a JSON object?
  27. How do I delete items from a dictionary while iterating over it?
  28. Counting each letter’s frequency in a string
  29. Checking a nested dictionary using a dot notation string “a.b.c.d.e”, automatically create missing levels
  30. How to create a Python dictionary with double quotes as default quote format?

Leave a Comment