In this post I am going to share what I learned about pickle. Pickle is to be eaten, in Python pickle is for data serializing and deserializing Python’s data object. Object in this case could be a variable, instance of a class, dictionaries, tuple and etc. Pickling is the process to convert data object into character streams. Before writing object into file, pickle serialize the object before writing it to a file. For deserializing data stream from file, unpickle can be used to convert data steam to object. Let’s see how the code look like to do this.

Pickle file

  # Import the pickle module
  import pickle

  #Create something to be pickled
  picklelist=['one',2,'three','four',5]
  
  # create a file
  file = open('pickletest_file','w')

  # dump object to file
  pickle.dump(picklelist, file)
  
  # pickling is completing, close the file
  file.close()

Unpickle file

  # import the pickle module
  import pickle

  # now open a file for reading
  unpicklefile = open('pickletest_file','r')

  # now load the list that we pickle into a new object
  unpickledlist = pickle.load(unpicklefile)

  # close the file
  unpicklefile.close()

  # print out every item in the unpickledlist
  for item in unpickledlist:
    print item

Output:

  one
  2
  3
  four
  5

One thing worth to note is that pickle has an optimized cousin, cpickle. Cpickle is writen in C, it is speed is 1000 times faster than pickle. Cpickle does not support subclassing of pickler() and unpickler(). Other than these, interfaces of the 2 modules are nearly the same.