How to construct a set out of list items in python

Question

I have a list of filenames in python and I would want to construct a set out of all the filenames   filelist    for filename in filelist      set filename    This does not seem to work  How can do this

User · Answer

One general way to construct set in iterative way like this   aset    e for e in alist

User · Answer

You can do my set   set my list   or  in Python 3  my set     my list   to create a set from a list  Conversely  you can also do my list   list my set   or  in Python 3  my list     my set   to create a list from a set  Just note that the order of the elements in a list is generally lost when converting the list to a set since a set is inherently unordered   One exception in CPython  though  seems to be if the list consists only of non-negative integers  but I assume this is a consequence of the implementation of sets in CPython and that this behavior can vary between different Python implementations

User · Answer

You can also use list comprehension to create set  s    i for i in range 5

User · Answer

The most direct solution is this  s   set filelist   The issue in your original code is that the values weren t being assigned to the set   Here s the fixed-up version of your code  s   set   for filename in filelist      s add filename  print s

User · Answer

Simply put the line   new list   set your list

User · Answer

If you have a list of hashable objects  filenames would probably be strings  so they should count    lst     foo py    bar py    baz py    qux py   Ellipsis    you can construct the set directly   s   set lst    In fact  set will work this way with any iterable object    Isn t duck typing great      If you want to do it iteratively   s   set   for item in iterable      s add item    But there s rarely a need to do it this way   I only mention it because the set add method is quite useful

User · Answer

Here is another solution    gt  gt  gt list1   C      D      E      C       gt  gt  gt set1 set list1   gt  gt  gt set1 set   E       D       C         In this code I have used the set method in order to turn it into a set and then it removed all duplicate values from the list

[python] How to construct a set out of list items in python?

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