Python

Basic

Think Python (Free Ebook)

http://www.greenteapress.com/thinkpython/

How to run a python code

python mypython.py

Install a new module

The Python Package Index (PyPI) is the definitive list of packages (or modules)

sudo apt-get install python-pip
pip install SomePackage
pip show --files SomePackage
pip install --upgrade SomePackage
pip uninstall SomePackage

If a package has been bundled by its creator using the standard approach to bundling modules (with Python’s distutils tool), all you need to do is download the package, uncompress it and type:

python setup.py install

How to list all installed modules

help('modules')

How to find the location of installed modules

There are different ways

1. python -v
2. import MODULENAME
3. help('MODULENAME')

Using this way, I find the 'RPi' module is installed under /usr/lib/python2.7/dist-packages.

if __name__ == "__main__":

http://stackoverflow.com/questions/419163/what-does-if-name-main-do

Import a compiled C module

• An example based on SWIG compiler.

string and string operators

Reference: Python for Genomic Data Science from coursera.

• Use double quote instead of single quote to define a string
• Use triple double quotes """ to write a long string spanning multiple lines or comments in a python script
• if dna="gatagc", then
  • dna[0]='g'
  • dna[-1]='c' (start counting from the right)
  • dna[-2]='g'
  • dna[0:3]='gat' (the end always excluded)
  • dna[:3]='gat'
  • dna[2:]='tgc'
  • len(dna)=6
  • type(dna)
  • print(dna)
  • dna.count('c')
  • dna.upper()
  • dna.find('ag')=3 (only the first occurrence of 'ag' is reported)
  • dna.find('17', 2) (start looking from pos 17)
  • dna.rfind('ag') ( search backwards in string)
  • dna.islower() (True)
  • dna.isupper() (False)
  • dna.replace('a', 'A')

Projects based on python

• pithos Pandora on linux
• Many Raspberry Pi GPIO projects
• GeneScissors It also requires pip and scikit-learn packages.
• KeepNote It depends on Python 2.X, sqlite and PyGTK.
• Zim It depends on Python, Gtk and the python-gtk bindings.
• Cherrytree It depends on Python2, Python-gtk2, Python-gtksourceview2, p7zip-full, python-enchant and python-dbus.

Qt for GUI development

• http://zetcode.com/gui/pyqt4/
• http://wiki.wildsong.biz/index.php/PyQt Create GUI in Qt Designer and convert/use it in PyQt.