Clear variable in python

Question

Is there a way to clear the value of a variable in python  For example if I was implementing a binary tree  class Node      self left   somenode1     self right   somenode2  If I wanted to remove some node from the tree  I would need to set self left to empty

User · Answer

var   None  clears the value   setting the value of the variable to  null  like value of  None   however the pointer to the variable remains    del var removes the definition for the variable totally    In case you want to use the variable later  e g  set a new value for it  i e  retain the variable  None would be better

User · Answer

The del keyword would do    gt  gt  gt  a 1  gt  gt  gt  a 1  gt  gt  gt  del a  gt  gt  gt  a Traceback  most recent call last     File   lt stdin gt    line 1  in  lt module gt  NameError  name  a  is not defined   But in this case I vote for self left   None

User · Answer

What s wrong with self left   None

User · Answer

Do you want to delete a variable  don t you  ok  I think I ve got a best alternative idea to  bnaul s answer  You can delete individual names with del  del x  or you can remove them from the globals   object  for name in dir        if not name startswith               del globals   name   This is just an example loop  it defensively only deletes names that do not start with an underscore  making a  not unreasoned  assumption that you only used names without an underscore at the start in your interpreter  You could use a hard-coded list of names to keep instead  whitelisting  if you really wanted to be thorough  There is no built-in function to do the clearing for you  other than just exit and restart the interpreter  Modules you ve imported  like import os  are going to remain imported because they are referenced by sys modules  subsequent imports will reuse the already imported module object  You just won t have a reference to them in your current global namespace

User · Answer

If want to totally delete it use del  del your variable   Or otherwise  to make the value None  your variable   None   If it s a mutable iterable  lists  sets  dictionaries  etc  but not tuples because they re immutable   you can make it empty like  your variable clear      Then your variable will be empty

User · Answer

I used a few options mentioned above     del self left   or setting value to None using   self left   None   It s important to know the differences and put a few exception handlers in place when you use set the value to None  If you re printing the value of the conditional statements using a template  say    print  The value of the variable is     format self left     you might see the value of the variable printing  The value of the variable is None   Thus  you d have to put a few exception handlers there    if self left       Then only print stuff    The above command will only print values if self left is not None

User · Answer

Actually  that does not delete the variable property  All it will do is set its value to None  therefore the variable will still take up space in memory  If you want to completely wipe all existence of the variable from memory  you can just type   del self left

[python] Clear variable in python

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