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This seems a bit odd! I did a program which required me removing duplicated from the list and choose the second last number. I did it using set(). however I came up with something unexpected.

set([32.0,36.0,39.0,40.0])

gives me an output of [32.0, 40.0, 36.0, 39.0]. I want to know why this happens. I'm using python 3.9.1 Thanks in advance

juanpa.arrivillaga
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Andrious Prime
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    This isn't odd. This happens because set objects have no order, the order you get from iterating over a set is not guaranteed (it's arbitrary but consistent within a process). This is generally a property of hash-based containers, although python dict objects *do* maintain insertion order despite being hash-based – juanpa.arrivillaga Feb 08 '21 at 17:43
  • Is there any function of removing duplicates while keeping the order? – Andrious Prime Feb 09 '21 at 06:12

2 Answers2

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Try below one

from collections import OrderedDict
list(OrderedDict.fromkeys([10,2,2,1,10,3,3]))
Guimoute
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Ram
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As you are using Python 3.7 or later you can use a dictionary instead of a set.

>>> l = [32.0,36.0,39.0,40.0]
>>> l[:] = list(dict.fromkeys(l))
>>> l
[32.0, 36.0, 39.0, 40.0]

The keys will be ordered by the order of insertion into the dictionary.

mhawke
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