OrderedDict

Fatma Kahveci
Coding
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  • Order is defined by the insertion order of keys.
  • OrderedDict is mutable.
  • Two functions differ from dict.

1. move_to_end()

move_to_end(<key>,<last>) # KeyError if <key> is not found. # <last>=True if to the end, <last>=False if to the beginning

  • It moves an item to the end or beginning.

2. popitem()

  • It pops efficiently from either end

  • You can check the equality of two dicts efficiently with OrderedDict.

  • seq (list, tuple)’s order is obvious.

  • set’s order is not known until it is created.

from collections import OrderedDict

###
nums = OrderedDict('one': 1,'two': 2)
nums.update('two':2.0) # preserves the order
reversed(nums)
#
keys= ['one', 'two']
OrderedDict.fromkeys(keys,0) # 'one': 0, 'two': 0
###