Python's cpickle for file access

The computer's memory is stored in a binary sequence (of course, in the Linux eye, it is a text stream ). We can directly fetch the data from the location of an object, convert it to a text stream (the process is called serialize), and then deposit the text stream into a file. Since Python is referring to the class definition of an object when creating an object, when we read the object from the text, we must have the class definition of the object handy to know how to reconstruct the object. When reading from a file, for Python's built-in (built-in) objects (such as integers, dictionaries, tables, and so on), it is not necessary for us to define classes in the program because their class definitions are already loaded into memory. However, for a user-defined object, you must define the class before you can load the object from the file .

In Python, the Pickle class can typically be used to serialize Python objects, while Cpickle provides a faster and simpler interface, as the python document says: "Cpickle-A faster pickle".

Cpickle can serialize any type of Python object, such as List,dict, even objects of a class. The so-called serialization, my superficial understanding is to be able to complete the preservation and can be completely reversible recovery. In Cpickle, there are four main functions that can do this work, as described in the following examples.

1, dump: Serializes the Python object to a local file.
>>> Import Cpickle
>>> data = range (1000)
>>> Cpickle.dump (Data,open ("Test\\data.pkl", "WB"))
The dump function needs to specify two parameters, the first is the Python object name that needs to be serialized, the second is a local file, and it is important to note that you need to use the Open function to start a file and specify a write operation.

2. Load: Load local file, restore Python object
>>> data = cpickle.load (open ("Test\\data.pkl", "RB"))
Like dump, you need to open a local file using the Open function and specify the "read" operation

3. Dumps: Serializes the Python object into a string variable.

>>> data_string = cpickle.dumps (data)

4. Loads: Loading a Python object from a string variable
>>> data = cpickle.loads (data_string)

"Source code Example"

Import h5pyimport Cpickle#data_path = ' f:\\20150727_1010\\feat_name.mat ' data_path = ' f:\\wfpdm\\20150727_1010\\feat_ Name.mat ' #data_path = ' h:\\wfpdm\\20150727_1010\\feat_name.mat ' Root_path = ' f:\\wfpdm\\20150727_1010\\ ' #root_path = "H:\\wfpdm\\20150727_1010\\" myfile=h5py. File (Data_path, ' r ') Data_set = [myfile[element[0]][:]. T-element in myfile[' feat_name '] #data = [myfile[element[0]][:]. T-element in myfile[' Feat_name ']] #print data[0].shape #print data[1].shapeprint data_set[0].shapemyfile.close () Filename= ' tst.pkl ' FID = open (Root_path+filename, ' WB ') cpickle.dump (Data_set,fid) fid.close () FIM = open (root_path+ FileName, "RB") LoadData = Cpickle.load (FIM) fim.close () print Loaddata[0].shape

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Python's cpickle for file access