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PythonCHBPythonCHB
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all the examples done -- I think.
1 parent 83fa76d commit 6b924d2

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Lines changed: 328 additions & 5 deletions

‎week-10/code/add_book_data.py‎

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'zip': "96543"},
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'email' : "PythonCHB@gmail.com",
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'home_phone' : "206-555-1234",
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'office"phone' : "123-456-7890",
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'office_phone' : "123-456-7890",
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'cell_phone' : "234-567-8901",
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},
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‎week-10/code/circle.py‎

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#!/usr/bin/env python
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"""
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circle class -- my solution to the exercise
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This version with doctests...
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"""
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import math
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class Circle(object):
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"""
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A class that defines a circle.
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You can get and set either the radius or the diameter with properties. Example:
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>>> c = Circle(4)
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>>> c.radius
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4.0
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>>> c.diameter
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8.0
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>>> c.diameter = 4
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>>> c.radius
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2.0
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>>> c.area
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12.566370614359172
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>>> c2 = Circle(6)
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>>> c + c2
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Circle(8.000000)
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>>> str(c2)
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'Circle Object with radius: 6.000000'
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>>>
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"""
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def __init__(self, radius):
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self.radius = float(radius)
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@property
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def diameter(self):
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return self.radius * 2.0
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@diameter.setter
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def diameter(self, value):
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self.radius = value / 2.0
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@property
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def area(self):
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return self.radius**2 * math.pi
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def __add__(self, other):
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return Circle(self.radius + other.radius)
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def __repr__(self):
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return "Circle(%f)"%self.radius
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def __str__(self):
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return "Circle Object with radius: %f"%self.radius
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if __name__ == "__main__":
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import doctest
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print doctest.testmod()

‎week-10/code/indent_etree.py‎

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#!/usr/bin/env python
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"""
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indenting function to pretty-print an ElementTree
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from:
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http://infix.se/2007/02/06/gentlemen-indent-your-xml
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why the %*#^ this isn't built-in to etree is beyond me.
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usage:
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indent(tree.getroot())
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tree.write(outfilename)
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"""
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def indent(elem, level=0):
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i = "\n" + level*" "
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if len(elem):
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if not elem.text or not elem.text.strip():
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elem.text = i + " "
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for e in elem:
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indent(e, level+1)
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if not e.tail or not e.tail.strip():
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e.tail = i + " "
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if not e.tail or not e.tail.strip():
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e.tail = i
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else:
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if level and (not elem.tail or not elem.tail.strip()):
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elem.tail = i
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‎week-10/code/pickle_example2.py‎

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#!/usr/bin/env python
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"""
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Example of how to save custom classes in a pickle
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"""
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import cPickle as pickle
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outfilename = "circles.pickle"
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### You can pickle a custom class, too:
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# remember the Circle class?
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import circle
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# create a couple of circles:
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C1 = circle.Circle(radius=2)
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print C1
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C2 = circle.Circle(radius=3.4)
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print C2
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# put them in a dict:
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circles = {'circle1': C1,
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'circle2': C2}
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#print circles
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## pickle the list
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pickle.dump(circles, open(outfilename, 'wb') )
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### see if we can re-load it
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## Note: the circle module needs to be available when you load the pickle
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circles2 = pickle.load( open(outfilename, 'rb') )
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# Haven't defined compare for the circle class:
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## extra credit -- add compare method (__cmp__) to Circle class
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same = True
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for c1, c2 in zip(circles.values(), circles2.values()):
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if c1.radius != c2.radius:
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same = False
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break
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if same:
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print "pickled/unpickled version is the same as the original"
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else:
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print "not the same"
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print circles
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print circles2

‎week-10/code/shelve_example.py‎

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#!/usr/bin/env python
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"""
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Example of how to save data in a shelf
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"""
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import shelve
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outfilename = "add_book_data.shelve"
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# get the data from the py file
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from add_book_data import AddressBook
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# since we can put a whole dict on a shelf:
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shelf = shelve.open(outfilename, 'n')
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for person in AddressBook:
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# create a key:
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key = "%(first_name)s%(last_name)s"%person
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shelf[key] = person
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shelf.close()
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## see if we can re-load it
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shelf2 = shelve.open(outfilename)
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AddressBook2 = [person for person in shelf2.values()]
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## note -- there could be an issue with order here.
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## so:
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AddressBook.sort()
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AddressBook2.sort()
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if AddressBook2 == AddressBook:
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print "shelved/unshelved version is the same as the original"
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‎week-10/code/xml_example.py‎

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#!/usr/bin/env python
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"""
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Example of how to save data as xml, using the element tree module
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This version stores all the data as attributes
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"""
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import xml.etree.ElementTree as ET
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from indent_etree import indent # for prettier output
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outfilename = "add_book_data.xml"
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# get the data from the py file
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from add_book_data_flat import AddressBook
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# build a tree structure
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root = ET.Element("address_book")
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# add the elements:
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for person in AddressBook:
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p = ET.SubElement(root, "person")
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# This method stores everything in attributes
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for key,value in person.items():
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p.set(key, value)
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# wrap it in an ElementTree instance, and save as XML
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tree = ET.ElementTree(root)
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indent(tree.getroot()) # to make it more pretty
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tree.write(outfilename)
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### See if we can re-load it
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tree = ET.parse(outfilename)
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book = tree.getroot()
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# re-build the original list:
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AddressBook2 = []
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for person in book.getchildren():
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#print person.attrib
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AddressBook2.append(person.attrib)
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if AddressBook2 == AddressBook:
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print "xml version is the same as the original"
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‎week-10/code/xml_example2.py‎

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#!/usr/bin/env python
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"""
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Example of how to save data as xml, using the element tree module
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This version does the full-on nested XML
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"""
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import xml.etree.ElementTree as ET
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from indent_etree import indent # for prettier output
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outfilename = "add_book_data2.xml"
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# get the data from the py file
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from add_book_data import AddressBook
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# build a tree structure
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root = ET.Element("address_book")
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# add the elements:
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for person in AddressBook:
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p = ET.SubElement(root, "person")
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# This method stores everything as sub-elements
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for key, value in person.items():
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if type(value) == dict:
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address = ET.SubElement(p, 'address')
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for sub_key, sub_value in value.items():
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sub_el = ET.SubElement(address, sub_key)
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sub_el.text=sub_value
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else:
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el = ET.SubElement(p, key)
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el.text=value
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# wrap it in an ElementTree instance, and save as XML
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tree = ET.ElementTree(root)
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indent(tree.getroot()) # to make it more pretty
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tree.write(outfilename)
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### See if we can re-load it
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tree = ET.parse(outfilename)
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book = tree.getroot()
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# re-build the original list:
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AddressBook2 = []
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for person in list(book):
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p = {}
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for sub_el in list(person):
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if sub_el.tag == "address":
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address = {}
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for sub_sub_el in sub_el.getchildren():
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t = sub_sub_el.text
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if t is None: ## etree returns None for empty tags!
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address[sub_sub_el.tag] = ""
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else:
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address[sub_sub_el.tag] = t
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p['address'] = address
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else:
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p[sub_el.tag] = sub_el.text
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AddressBook2.append(p)
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if AddressBook2 == AddressBook:
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print "xml version is the same as the original"
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else:
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print "xml version is not exactly the same as the original"

‎week-10/presentation-week10.pdf‎

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Binary file not shown.

‎week-10/presentation-week10.tex‎

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re-writing them to the db.}\\
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(or use writeback=True)
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\vfill
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{\Large Suffers from some of the same portability issues as \verb|anydbm|}
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\vfill
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{\Large If less that 100s of MB -- just use a dict and pickle it}
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\vfill
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\url{http://docs.python.org/library/shelve.html}
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\end{frame}
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\vfill
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{\Large \verb|xml.etree|: }
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\url{http://docs.python.org/library/xml.etree.elementtree.html}
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\end{frame}
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% ---------------------------------------------
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\begin{frame}[fragile]{elementtree}
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\vfill
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{\Large The Element type is a flexible container object, designed to store
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hierarchical data structures in memory.}
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\vfill
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{\Large Essentially an im-memory XML -- can be read from written-to XML}
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\vfill
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{\Large an \verb|ElementTree| is an entire XML doc}
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\vfill
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{\Large an \verb|Element| is a node in that tree}
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\vfill
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\url{http://docs.python.org/library/xml.etree.elementtree.html}
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\end{frame}
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\begin{frame}[fragile]{INI}
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{\Large INI files}
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\begin{frame}[fragile]{DB-API}
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\vfill
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{\Large The DB-API spec (PEP 249) is a specification for interation between Pyton and Relational Databases.}
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{\Large The DB-API spec (PEP 249) is a specification for interaction between Python and Relational Databases.}
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\vfill
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{\Large Support by a large number of third-party Database drivers:
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{\Large Support for a large number of third-party Database drivers:
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\begin{itemize}
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\item MySQL
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\item PostgreSQL
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% ---------------------------------------------
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\begin{frame}[fragile]{Object-Relation Mappers}
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{\LARGE ORMs}
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\vfill
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{\Large Systems for mapping PYton objects to tables in a RDBMS}
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{\Large Systems for mapping Python objects to tables in a RDBMS}
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\vfill
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{\Large Saves you writing that glue code}
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{\Large Saves you writing that glue code (and the SQL) }
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\vfill
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{\Large usually deals with mapping to various back-end RDBMSs}

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