study notes for python

some useful materials

Python完全新手教程

http://www.cnblogs.com/taowen/articles/11239.aspx (from taowen, BITer)

Note:

Part 1 Basic Data Structure

List, Dict(dictionary) and Turple are three main data structures in python, which are respond to set,mapping and ? in math.

List

my_list=[]
my_list=[1,2]
print my_list
my_list.append(3)
print my_list

list can be indexed: print my_list[1], which outputs 2

Dict

contact={}
contact["name"]="taowen"
contact["phone"]=68942443

Turple

my_turple = (1,2,3)
my_list = []
for i in my_turple:
    my_list.append(i)
print my_list

Part 2 Basic Grammer

i = 5
n = 0
while i>0:
    n = n + i
    i = i - 1
print n

while 1:
　　inputed_num = input("input a number between 1 and 10\n")
　　if inputed_num >= 10:
　　　　pass
　　elif inputed_num < 1:
　　　　pass
　　else:
　　　　break
print "hehe, don't follow, won't out"

Part 3 IO

raw_input: return your inputs as a string.

input:convert your inputs to a digital number and return it.

COFFE BREAK

# import the module to create a GUI
fromt Tkinter import *
# create a main window
root = Tk()
# create a label which is located in the main window
w = Label(root, text="Hello, world!")
# put the label in main window in default way
w.pack()
# start a loop waiting for your input
root.mainloop()

Part 4 Exception Handling

try:
    print input()
except:
    print "there is an error in your input"

Part 5 Function

def square(x):
    return x**2
print square(5)

def swap(a,b):
# return a turple
　　return (b,a)
print swap(1,2)

Whether the paramater in function can be modifed or not depends on the type of paramater. Data types such as number or string cannot be modified in funciton, while list could be modified when used as param. So it's better to think twice before sending the complex params to function(you may need to copy it in advance).

Part 6 File Operation in Python

#input
xxx = file('c:\\a.txt', 'r')
xxx_content = infile.read()
xxx_content = infile.readlines()
for xxx_line in xxx.readlines():
    print "Line:", xxx_line
xxx.close()

#output
xxx=file('c:\\test.txt','w')
xxx.write("billrice")
xxx.write("testtest")
xxx.write("enter\n")
xxx.writelines(['billrice','ricerice'])
xxx.close

Note that before running the xxx.close() sentence, there is just an empy test.txt file in C disk, xxx.close() completes the save operation.

COFFE BREAK : useful functions

eval(raw_input())
# input 1+2, output 3

Part 7 Class

class person:
　　 school = 'bit'
    def _init_(self):
        self.name = 'taowen'
        self.id = 20022479
    def say_id(self):
        print "%s's id is %d" % (self.name, self.id)

me = person()
me.say_id()