jupyter delete all variables after cell

Question

How can I delete all variables in jupyter that are defined / created after a certain cell number?

My specific use case is that I will load some variables in the first few cells and I want to keep those variables, while I will experiment on the notebook.

I do not want to keep restarting or reseting the notebook as it takes time to load those variables. Instead I would like to "restart" from a certain cell.

FabienP · Accepted Answer · 2017-08-29 20:27:45Z

2

If you can afford the memory and duplicate the variables, store "backup" variables using something like copy.copy() or copy.deepcopy() and create a cell were you reallocate original values to your variables from the backups.

You'll have run this cell to restore your values.

see edit details below

For illustration:

Store original values

from copy import deepcopy

bckp_a = deepcopy(var_a)
bckp_b = deepcopy(var_b)

dir_bckp = deepcopy(dir())  # store defined variables defined at this point

Do you stuff

var_a = some_func(var_a)
var_b = some_other_func(var_a)
var_c = some_value

Restore original values for preserved variables

var_a = deepcopy(bckp_a)
var_b = deepcopy(bckp_b)

Delete newly created variables

for var in dir():
    if var == 'dir_bckp':      # Note that it is a string
        continue                   # Preserve dir_bckp, very important.
    elif var not in dir_bckp:
        del globals()[var]     # Delete newly defined variables

>>> var_c
NameError: name 'var_c' is not defined

EDIT:

If you absolutely need to delete created variables, you can try a trick with dir() and globals(). But this is probably not good practice, so be cautious.

See changes above.

Note that there is also the option of creating a restore point using Pickle, but I'm not sure of the performance if some variables take time to load.

edited Aug 29, 2017 at 20:27

answered Aug 28, 2017 at 22:05

FabienP

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4 Comments

hangc Over a year ago

So with the backup variables, I am interested in knowing how that can help to delete other variables

FabienP Over a year ago

Once variable values restored, re-run and garbage collector will do his job. If you really want to delete these variables, you can backup dir() and restore it. But this is a trick, I doubt it is good practice. I will explain in a edit.

FabienP Over a year ago

@user113531: is it what you were looking for?

hangc Over a year ago

Sorry missed your reply. It is working, and doesn't sounds like a good practice to me as well. Would like to hear your idea on why it is not a good practice.

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