Random module - another example

Random module is a module used in everyday programming.
Even if it is not used in the final software, he helps us to test various types of random data.
We present you a simple example - play with cards.
We chose a list of cards of one color for not having a large number of elements.
We exemplify the use of random module by analogy with a game of cards.
That it means: shuffle cards , select just one from cards and a choice selection of a defined number of cards.
Below you see the code used as an example.

>>> import random
>>> choice=random.choice
>>> shuffle=random.shuffle
>>> for i in range (9):
...     print choice(cards)
... 
Q
K
10
Q
2
2
10
K
6
>>> shuffle(cards)
>>> cards
[4, 7, 10, 'J', 3, 'Q', 6, 2, 'K', 9, 'A', 8, 5]
>>> sample=random.sample
>>> sample(cards,5)
[8, 'J', 2, 'Q', 10]
>>> sample(cards,5)
['A', 9, 4, 'K', 'Q']
>>> 

The random module docs

The module matplotlib-0.99.3

The module matplotlib is a python 2D plotting library with a variety of hardcopy formats and interactive environments across platforms.
With just a few lines of code we can generate plots, histograms, power spectra, bar charts, errorcharts, scatterplots, etc...
See images bellow or visit the gallery.

This module is version 0.99.3 for Python 2.5 and 2.6. We have modules for installation on operating systems like MacOS, Windows and Linux.
To use this module you must have install numpy module.
Now download module from here.

$python setup.py build

Use super user:

#python setup.py install

Try to load module:

$python
Python 2.5.1 (r251:54863, Jun 15 2008, 18:24:51) 
[GCC 4.3.0 20080428 (Red Hat 4.3.0-8)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import matplotlib
>>> 

It's working fine.

Add text on image with PIL module.

It's easy to create images with PIL module.
This is the script:

import PIL
from PIL import ImageFont
from PIL import Image
from PIL import ImageDraw
font = ImageFont.truetype("/usr/share/fonts/dejavu/DejaVuSans.ttf",25)
img=Image.new("RGBA", (200,200),(120,20,20))
draw = ImageDraw.Draw(img)
draw.text((0, 0),"This is a test",(255,255,0),font=font)
draw = ImageDraw.Draw(img)
draw = ImageDraw.Draw(img)
img.save("a_test.png")

The only error that can occur is not to find the font.
In this case you must change the code line:

font = ImageFont.truetype("/usr/share/fonts/dejavu/DejaVuSans.ttf",25)

Here is the result script:

The HTMLParser module - just simple example

Basically this module is for parsing text files formatted in HTML (HyperText Mark-up Language) and XHTML.
On HTMLParse docs.
You will see the same example but with no explanation. The example is :

import HTMLParser
from HTMLParser import *
import urllib2 
from urllib2 import urlopen

class webancors(HTMLParser):
 def __init__(self, url):
  HTMLParser.__init__(self)
  r = urlopen(url)
  self.feed(r.read())

 def handle_starttag(self, tag, attrs):
  if tag == 'a' and attrs:
   print "Link: %s" % attrs[0][1]

I named the python file : spiderweb.py
I use python to import this file:

>>> import spiderweb
>>> spiderweb.webancors('http://www.yahoo.com')
Link: y-mast-sprite y-mast-txt web
Link: y-mast-link images
Link: y-mast-link video
Link: y-mast-link local
Link: y-mast-link shopping
Link: y-mast-link more
Link: p_13838465-sa-drawer
Link: y-hdr-link

>>> 

The method handle_starttag takes two arguments from HTMLParser.
This arguments, tag and attrs is used to return values.
Note :
The HTMLParser module has been renamed to html.parser in Python 3.0. The 2to3 tool will automatically adapt imports when converting your sources to 3.0.
Use "http://" not just "www". If don't use "http://" you see errors.
Seam urllib2 have some troubles with:

  File "/usr/lib/python2.5/urllib2.py", line 241, in get_type
    raise ValueError, "unknown url type: %s" % self.__original

You can use all functions HTTParser class.