Python Programming for Biology: Bioinformatics and Beyond

Method

(pickle.)

Description

dump(obj, file,

protocol)

Saves a copy of a Python object to disk, as a serialised Pickle

file, using a specified file object.

load(file)

Loads a Python object saved as a serialised Pickle file into

memory.

dumps(obj,

protocol)

Creates a serialised Pickle string that represents a given object.

loads(string)

Creates a Python object from a serialised Pickle string version.

The ‘

sys

’ module

The sys module contains information that relates to the Python interpreter and its runtime

environment. As with the os module (which is for operating-system interaction) we only

focus on some of the more commonly used functionality.

Attribute/Method

(sys.)

Description

argv

Retrieves a list that contains the command line arguments

that were passed in when Python was run, starting with the

name of the Python script.

exit(code)

Quits the current Python session/program, optionally

passing back a specific exit status code to the system.

modules

Retrieves a dictionary that contains all of the currently

imported modules as (module name: file path), key, value

pairs.

path

Retrieves a list of strings representing the Python module

look-up paths. Starts with the value from the

PYTHONPATH environment variable. This list of paths can

---

be modified programmatically.

platform

Retrieves a string indicating what basic kind of computer

system Python is running on, i.e. indicating Windows, Mac

OS X, Linux etc.

stdin

Retrieves a file object that represents standard input, where

textual input is taken from, which by default is the keyboard.

stdout

Retrieves a file object that represents standard output to the

screen, where textual output, in the absence of a specific file,

is sent. This is what print writes to by default.

stderr

Retrieves a file object that represents standard error output;

usually to screen, unless otherwise redirected.

version

Retrieves a string indicating which version of Python is

being used.