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