Tutorial

Python’s random module makes it extremely easy to generate random DNA bases.

import random
dna = ["A","G","C","T"]
#output a random base
print(random.choice(dna))

Now to generate a specific number of random bases, all we have to do is use Python’s range function:

The main use I’ve found for the Python sys module is allowing command-line arguments to be made to a script. Here is an example of how it looks:

import sys

if len(sys.argv) == 2:
    input_file = sys.argv[1]
else:
    print "Please input a command-line argument specifying the file"

This script checks that 2 command-line arguments had been passed to the program before assigning the value sys.argv[1] to a variable. We check for two command-line arguments because the first one (sys.argv[0]) is the name of the Python script currently being executed.

You can use the Python os module to send commands out to the operating system. Through os you can do anything from changing the current working directory through to listing the contents of a directory.

import os

# print the current working directory
print os.getcwd()
# change the working directory
os.chdir("..")
# create a new directory
os.mkdir("new_folder")
# list the contents of a directory
os.listdir("new_folder")
# remove directory
os.rmdir("new_folder")
# remove a file
os.remove("image.jpg")
# rename a file/directory and where it will go
os.rename("/data/jack", "/james")