Is there a way to delete created variables functions etc from the memory of the interpreter

Question

I ve been searching for the accurate answer to this question for a couple of days now but haven t got anything good  I m not a complete beginner in programming  but not yet even on the intermediate level   When I m in the shell of Python  I type  dir   and I can see all the names of all the objects in the current scope  main block   there are 6 of them       builtins        doc        loader        name        package        spec       Then  when I m declaring a variable  for example x   10  it automatically adds to that lists of objects under built-in module dir    and when I type dir   again  it shows now       builtins        doc        loader        name        package        spec      x     The same goes for functions  classes and so on     How do I delete all those new objects without erasing the standard 6 which where available at the beginning   I ve read here about  memory cleaning    cleaning of the console   which erases all the text from the command prompt window      gt  gt  gt  import sys  gt  gt  gt  clear   lambda  os system  cls    gt  gt  gt  clear     But all this has nothing to do with what I m trying to achieve  it doesn t clean out all used objects

User · Answer

If you are in an interactive environment like Jupyter or ipython you might be interested in clearing unwanted var's if they are getting heavy.

The magic-commands reset and reset_selective is vailable on interactive python sessions like ipython and Jupyter

1) reset

reset Resets the namespace by removing all names defined by the user, if called without arguments.

in and the out parameters specify whether you want to flush the in/out caches. The directory history is flushed with the dhist parameter.

reset in out

Another interesting one is array that only removes numpy Arrays:

reset array

2) reset_selective

Resets the namespace by removing names defined by the user. Input/Output history are left around in case you need them.

Clean Array Example:

In [1]: import numpy as np
In [2]: littleArray = np.array([1,2,3,4,5])
In [3]: who_ls
Out[3]: ['littleArray', 'np']
In [4]: reset_selective -f littleArray
In [5]: who_ls
Out[5]: ['np']

Source: http://ipython.readthedocs.io/en/stable/interactive/magics.html

User · 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  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

Actually python will reclaim the memory which is not in use anymore This is called garbage collection which is automatic process in python  But still if you want to do it then you can delete it by del variable name  You can also do it by assigning the variable to None   a   10 print a   del a        print a         throws an error here because it s been deleted already    The only way to truly reclaim memory from unreferenced Python objects is via the garbage collector  The del keyword simply unbinds a name from an object  but the object still needs to be garbage collected  You can force garbage collector to run using the gc module  but this is almost certainly a premature optimization but it has its own risks  Using del has no real effect  since those names would have been deleted as they went out of scope anyway

User · Answer

Yes  There is a simple way to remove everything in iPython   In iPython console  just type    reset   Then system will ask you to confirm  Press y  If you don t want to see this prompt  simply type    reset -f   This should work

User · Answer

You can use python garbage collector   import gc gc collect

User · Answer

This worked for me   You need to run it twice once for globals followed by locals  for name in dir        if not name startswith               del globals   name   for name in dir        if not name startswith               del locals   name

[python] Is there a way to delete created variables, functions, etc from the memory of the interpreter?

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