How to use "try" ... "except"

Any program will be given over to error checking.
Python provides an exception handling capability.
There are two parts : "error checking" "catching exceptions".
Now let's try a simple example:

>>> try :
...     input_str = int(input ("string "))
... except StandardError :
...     print " This is not a number"
... 
string 12
>>> try :
...     input_str = int(input ("string "))
... except StandardError :
...     print " This is not a number"
... 
string aaa
 This is not a number

The code :

input_str = int(input ("string "))

The code readed input will be convert in integer .
If types a value that's not an integer, the exception is caught.
In this case will print " This is not a number ".
This is very important because it generates more errors while running a program.
So, simply try to perform you action, and define what's to be done.
On except block if the action you want can't be completed.

Permutation of chars with python

It is a simple example of using python language to permutation of chars.
It uses a list generator and "yield":

#!/usr/bin/env python
def permut(lst):
    remove = lambda lst0, index: lst0[:index] + lst0[index+1:]
    if lst:
        for index, x in enumerate(lst):
            for y in permut(remove(lst, index)):
                yield (x,)+y
            print y 
                
    else: yield ()
lst='catalin'
for p in permut(['c','a','t','a','l','i','n']):
    print p

Example can be modified so output will be a file.

Google and Python Stuff

I want share this scripts.
Is just two scripts and i think is beautifull.
First is a youtube script :

import gdata.youtube
import gdata.youtube.service

client_yt = gdata.youtube.service.YouTubeService()
query = gdata.youtube.service.YouTubeVideoQuery()
query.vs = "%s" % ('News')
feed = client_yt.YouTubeQuery(query)

for entry in feed.entry:
print entry.title.text
for link in entry.link:
if link.rel == 'alternate':
print link.href

Second is a picassa script :

import gdata.photos
import gdata.photos.service
import urllib
p_client = gdata.photos.service.PhotosService()

query_parameters = map(urllib.quote, ['Sexy','Bucharest']);
feed = p_client.GetFeed("/data/feed/api/all?q=%s%s&max-results=10" % ('Sexy','Girl'))

for entry in feed.entry:
print entry.title.text
for link in entry.link:
if link.rel == 'alternate':
print link.href

I hope you like this little scripts.

Sqlite and Python

These script explore the Python Sqlite modules available for database administration.
Sometime you need to use extraction, processing, storage and presentation of your data.
This is a short example :

#!/usr/bin/python

import sqlite3

def select_db():
print "Select database"

co=sqlite3.connect("cata2.db")
cursor=co.execute("CREATE TABLE report (nr INT,user VARCHAR(20),descriere VARCHAR(100));")
cursor=co.execute("INSERT INTO report (nr,user,descriere) VALUES (1,'root','root administration');")
cursor=co.execute("SELECT * FROM report;")

print cursor.fetchall()

This python script will be create cata.db file on your folder.
The table of database is 'report' and add next values "1,'root','root administration'".
If you want create new database , use :

co=sqlite3.connect("new_database.db")
cursor=co.execute("CREATE TABLE tabela (some_value_integer INT,some_value_chars VARCHAR(20));")

If you want show it , use this :

cursor=co.execute("SELECT * FROM new_database;")

Thank you !

resize images to create thumbnails

First you have many images.
If you want to create thumbnail for each one this is python script:

import glob 
import PIL
from PIL import Image
for infile in glob.glob("*.jpg"):
 img = Image.open(infile)
 dim_percent=(100/float(img.size[0]))
 dim_size=int((float(img.size[1])*float(dim_percent)))
 img = img.resize((100,dim_size),PIL.Image.ANTIALIAS)
 if infile[0:2] != "trumb_":
  img.save("trumb_" + infile, "JPEG")

PyGTK and GdkPixbuf

What is GdkPixbuf?
* An object holding information about images in memory.
Constructor
GdkPixbuf (GdkColorspace colorspace, bool has_alpha, int bits_per_sample, int width, int height);

Example:

>>> import pygtk
>>> import pygtk
>>> pixbuf = gtk.gdk.Pixbuf( gtk.gdk.COLORSPACE_RGB, False,8, 200, 100)
>>> pixbuf.save('/home/net/cc/a.jpg','jpeg', {'quality':'100'})

The output is :

PyGTK 2.15.2 - unstable

As you know, PyGTK is a set of Python wrappers.
Now PyGTK easily create programs with a graphical user interface using the Python programming language.
The new PyGTK version 2.15.2 and is on PyGTK 2.15.2 source.
From http://pygtk.org
"What's new since 2.15.0?
- (Add HSV support to gtk.gdk.Color objects)
- Add floating-point support to gtk.gdk.Color (Paul)
- Retire hand-written ChangeLog; autocreate from Git history (Paul)
- Fix conditional in docs/Makefile.am (Frederic Peters)
- Document that gtk.gdk.GC coordinates are not related to allocation (Paul)
- Make pygtk_boxed_unref_shared() also handle Py_None (Paul)
- Make gtk.MenuItem.set_submenu accept None (Paul)
- Don't run 'fixxref.py' if documentation is not built (Björn Lindqvist)
- Apply libtool 2.2 compatibility patch (Gian)
- Plug reference leak on main signal watch source (Paul)
- Add extra warning against accidental misuse of tree model columns (Paul)
- Wrap gtk.Border attributes and constructor (Mariano Suárez-Alvarez)
- Make gtk.gdk.Event.time accept 'long' in assignments (Paul)
- Wrap gtk.RcStyle attributes (Paul)

PyGTK requires GTK+ >= 2.8.0 and Python >= 2.3.5 to build."

Python - random passwords

This program generates passwords on the size of 10 characters.
By using a function called "random_password" that creates a password of size 10 characters.
This function called "write_file" creates a file with automatic redial function "random_password. It contains a table of 10 X 10 random passwords.

from random import *
import string
chars = string.ascii_letters + string.digits
def random_password():
 a = "".join(choice(chars) for x in range(randint(10, 10)))
 b  = a + ' | '
 return b
def write_file():
 f = open('random_pass.txt', 'wr+')
 for c in range(10):
  rand=''
  for r in range(10):
   rand = rand + random_password() 
  randpass=rand + random_password() + '\n'   
  f.write(str(randpass))
 f.close()
write_file()

Python and xml

Python is an excellent choice for writing programs that process XML data.
XML's is a simplified subset of the Standard Generalized Markup Language (SGML).
He set of tools helps developers in creating web pages.
This is one simple example which I use with "conky":

from xml.dom import minidom as dom
import urllib2
def fetchPage(url):
    a = urllib2.urlopen(url)
    return ''.join(a.readlines())
def extract(page):
    a = dom.parseString(page)
    item2 = a.getElementsByTagName('SendingDate')[0].firstChild.wholeText
        print "DATA ",item2
    item = a.getElementsByTagName('Cube')
    for i in item:
        if i.hasChildNodes() == True:
                e = i.getElementsByTagName('Rate')[8].firstChild.wholeText
        d = i.getElementsByTagName('Rate')[18].firstChild.wholeText
                print "EURO  ",e
        print "DOLAR ",d

if __name__=='__main__':
    page = fetchPage("http://www.bnro.ro/nbrfxrates.xml")
    extract(page)

First step ...and some examples

So the first step to use python is how to load module.
This is simple one:

import sys
import math
from math import sin
dir(math)

['__doc__', '__file__', '__name__', 'acos', 'asin', 'atan', 'atan2', 'ceil', 'cos', 'cosh', 'degrees', 'e', 'exp', 'fabs', 'floor', 'fmod', 'frexp', 'hypot', 'ldexp', 'log', 'log10', 'modf', 'pi', 'pow', 'radians', 'sin', 'sinh', 'sqrt', 'tan', 'tanh']

Next is two examples with calendar module.

import calendar
time_cal=calendar.TextCalendar(calendar.FRIDAY)
print time_cal.formatmonth(2009,02)
 February 2009
Fr Sa Su Mo Tu We Th
     1  2  3  4  5
6  7  8  9 10 11 12
13 14 15 16 17 18 19
20 21 22 23 24 25 26
27 28

If i use this into web page this is the solution:

import calendar
html_cal=calendar.HTMLCalendar(calendar.MONDAY)
print html_cal.formatmonth(2009,02)

February 2009
Mon
Tue
Wed
Thu
Fri
Sat
Sun






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About Python

Python is like a knife to a developer.

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Python is a remarkably powerful dynamic programming language.
Python runs on Windows, Linux/Unix, Mac OS X, OS/2, Amiga, Palm Handhelds, and Nokia mobile phones. Python has also been ported to the Java and .NET virtual machines.

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Python is distributed under an OSI-approved open source license that makes it free to use, even for commercial products.

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