Learning Python -- Part two

1. Dictionary

    dic = {'lilei':90,'lily':100,'sam':57, ''tom" :90}
   
    for key in dic
        print dic[key]

    print dic.keys(),  return all keys
            dic.values(), return all values
            dic.items(),  return all element
            dic.clear(),  clear dic, dic become {}

   del dic['tom']  , delete 'tom' in dic, del is the keyword
   
2. file
   
    f = open(filename, mode), "r" read, "w" write
    content  = f.read(N) , read N bytes data
    content  = f.readline(), read one line
    content = f.readlines(), read all the lines

    f.write('I like apple'), write to file

    f.close()

3. range(), enumerate(), zip()
    S = 'abcdefghijk'
    for i in range(0,len(S),2):
        print S[i]
 
    for (index,char) in enumerate(S):
        print index
        print char
 
    ta =[1,2,3]
    tb = [9,8,7]
    tc = ['a','b','c']
    for (a,b,c) in zip(ta,tb,tc)
        print(a,b,c)

    ta = [1,2,3]
    tb = [9,8,7]
    zipped = zip(ta,tb)
    print(zipped)

    na,nb = zip(*zipped)
    print(na,nb)


4. lambda
    func = lambda x,y: x+ y
    print func(3,4)

    def teset(f,a,b):
        print 'test'
        print f(a,b)
   test(func,3,5)

   test((lambda x: x+3),[1,3,5,6])

5. map
    re = map((lambda x,y: x+y),[1,2,3],[6,7,9])

6. filter
    def func(a)
        if a> 100:
            return True
        else:
            return False

   print filter(func,[10,56,101,500])

7. reduce
    print reduce((lambda x,y: x+y),[1,2,5,7,9])

8.  debug
     re = iter(range(5))

     try:
         for i in range(100):
             print re.next()
     except StopIteration:
         print 'Here is end ',i
    print 'HaHaHa'


    try:
        ...
    except error1:
        ...
    except error2:
        ...
    else:
        ...
    finally:
        ...

Learning Python - part one

1.  print 'Hello World'
     a = 10
     print a
     print type(a)
 
     a = 1.3
     print a
     print type(a)

     basic type:
     a = 10     int     a =1.3 float       a = True  True/False    a = 'Hello'  string
     type() - return data type
 
 2.  Sequence:
      Tuple : s1 = (2, 1.3, 'love',9,12,false)  , element can not be change
     
      List: s2 = [True, 5, 'smile']  , element can change

      print s1[0]
      print s2[2]
      s2[1] = 3.0
      print s2

      print s1[:5]  -- from start to element 4
      print s1[2:]  -- from element 2 to last
      print s1[0:5:2]  -- from index 0 to element 4 , every 2 to get a element, such as element 0,2,4
      print s1[2:0:-1] -- from element 2 to element 1

      print s1[-1] -- last element
      print s1[-3] -- the last third element

3. If else
    i = 1
    if i>0:
        print 'positive i'
        i = i+1
    elif i ==0:
        print 'i is 0'
        i = i *10
    else:
       print 'negative i'
       i = i -1
    print 'new i:',i

4.  for, while, continue, break
   
     for a in [3,4.4, 'lift']:
         print a

     while i< 10:
         print i
         i = i+1

5. function
    def square_sum(a,b)
        c = a**2 + b ** 2
        return c

    print square_sum(3,4)

6. class , object
    class Bird(object)
        have_feather = True
        way_of_reproduction = 'egg'
        def move(self,dx,dy):
            position =[0,0]
            position[0] = position[0]+dx
            position[1] = position[1] +dy
            return position

 summer = Bird()
 print 'after move:', summer.move(5,8)

 class Chicken(Bird):
     way_of_move = 'walk'
     possible_in_KFC = True

summer = Chicken()
print summer.have_feather
print summer.move(5,6)


7. dir(), help()
    print dir(list)
    print help(list)

    n1 = [1,2,5,3,5]
    n1.count(5),   how many 5
    n1.index(3),   index of the first 3
    n1.append(6), add 6 to the list
    n1.sort(), sort
    n1.pop(), remove the last element and return it
    n1.remove(2), remove the first 2
    n1.insert(0,9), insert 9 to position 0