How pickle object and transfer between files in python? - class

Question

I have a class that I want to share between different files or computers? I can pickle and load it from the same jupyter notebook. However, I cannot load it from a different machine/or different notebook. I have tried the following,
Initialize and and save from a jupyter notebook
# Simplified class definition
class MyClass:
def __init__(self, name):
self.name = name
self.dataToIndex = {}
self.index = 0
def addData(self, dataReceived):
self.dataToIndex[dataReceived] = self.index
self.index += 1
# initialize
my_dataset = MyClass("My_test_dataset")
# add some data
my_dataset.addData("One")
my_dataset.addData("Two")
# check data
my_dataset.dataToIndex
# save from one juputer notebook
import pickle
with open("path.obj", "wb") as inp:
pickle.dump(my_dataset, inp, pickle.HIGHEST_PROTOCOL)
# Read from the same jupyter notebook
with open("path.obj", 'rb') as inp:
transferred = pickle.load(inp)
# Output looks good
transferred.dataToIndex
{'One': 0, 'Two': 1}
Read from the new jupyter notebook
import pickle
with open("path.obj", 'rb') as inp:
transferred = pickle.load(inp)
---------------------------------------------------------------------------
AttributeError Traceback (most recent call last)
<ipython-input-1-44a1a18ebb1b> in <module>
2 # Read from the same jupyter notebook
3 with open("path.obj", 'rb') as inp:
----> 4 transferred = pickle.load(inp)
AttributeError: Can't get attribute 'MyClass' on <module '__main__'>
Now, I want to be able to load into a different python script on in a different jupyter notebook.
I have checked this, Saving an Object (Data persistence)
and
https://www.stefaanlippens.net/python-pickling-and-dealing-with-attributeerror-module-object-has-no-attribute-thing.html
But could not figure out a solution. Any help is appreciated.

Answer 1

There is a tons of helpful posts on this. However, most of those fall under, how to save from within the class etc. For a future beginner like me, I just want to provide a simple solution that worked for me.
Take the class out of the notebook and put in a script like, my_class_def.py
class MyClass:
def __init__(self, name):
self.name = name
self.dataToIndex = {}
self.index = 0
def addData(self, dataReceived):
self.dataToIndex[dataReceived] = self.index
self.index += 1
Then use the pickle to save as it is.
In the different(new) script, import the class first using,
from my_class_def import MyClass
and then load the picked file.