How to save a list to a file and read it as a list type?

Question

Say I have the list score=[1,2,3,4,5] and it gets changed whilst my program is running. How could I save it to a file so that next time the program is run I can access the changed list as a list type?

I have tried:

score=[1,2,3,4,5]  with open("file.txt", 'w') as f:     for s in score:         f.write(str(s) + '\n')  with open("file.txt", 'r') as f:     score = [line.rstrip('\n') for line in f]   print(score) 

But this results in the elements in the list being strings not integers.

Answer 1

You can use the pickle module for that. This module has two methods,

1. Pickling(dump): Convert Python objects into a string representation.
2. Unpickling(load): Retrieving original objects from a stored string representation.

https://docs.python.org/3.3/library/pickle.html

Code:

>>> import pickle >>> l = [1,2,3,4] >>> with open("test", "wb") as fp:   #Pickling ...   pickle.dump(l, fp) ...  >>> with open("test", "rb") as fp:   # Unpickling ...   b = pickle.load(fp) ...  >>> b [1, 2, 3, 4] 

---

Also Json

1. dump/dumps: Serialize
2. load/loads: Deserialize

https://docs.python.org/3/library/json.html

Code:

>>> import json >>> with open("test", "w") as fp: ...     json.dump(l, fp) ... >>> with open("test", "r") as fp: ...     b = json.load(fp) ... >>> b [1, 2, 3, 4]