sequence
Lists, tuples, strings
Common ground:
1. You can get each element by index
2. The default index starts from 0
3. You can get a set of elements within a certain range in the form of slices
4. Many common operators, *, +, in/not in
Data with the above characteristics is a sequence (list, tuple, string)
· Built-in functions for sequences (BIFs)
1. List list()/list(iterator)
Convert an iterable object to a list
a='Hello'
print (list(a))#['H', 'e', 'l', 'l', 'o']
2. tuple()/tuple(iterator)
converts an iterable object into a tuple
a='Hello'
print (tuple(a))#('H', 'e', 'l', 'l', 'o')
3, str (object): object is converted to a string
print str(10)#字符串10
4. len(...): Returns the length of a parameter
a='Hello'
print len(a) #5
5. max(): Returns the maximum value in the sequence or parameter set
l=[1,2,3,4,5]
print max(l) #5
6. min(): Returns the minimum value of a sequence or set
l=[1,2,3,4,5]
print min(l) #1
l=['a','b','c']
print max(l)#c ASCII 对应数值大
l=[1,2,3]
l.append('a')
print l #[1, 2, 3, 'a']
print min(l) #1
print max(l) #a的编码表为97 返回a
这个比较在python2 可以,如果python3不同类型比较报错
7. sum(iterator[,start=0]): Returns the sum of iterable objects and optional parameters
a=[1,2,3]
print sum(a) #6
print sum(a,10) #16
8. sorted(): sort() is similar to: sorting
a=[3,1,2]
print sorted(l) #[1,2,3]
9. reversed(): reverse() iterates objects in reverse order
a=[4,5,3,8,1]
print reversed
list(reversed(sorted(a)))
print a #[8,5,4,3,1]
#如果直接reversed(sorted(a))不行 这是可迭代对象 必须加list
10. enumerate(): Returns the tuple sequence (subscript, element) iterable object
l=['a','b','c']
print list(enumerate(l))
#[(0, 'a'), (1, 'b'), (2, 'c')]
11. zip(): Return the packaged tuple
a=[1,2,3,4,5,6,7,8]
b=[4,5,6,7,8]
print list(zip(a,b))
#[(1, 4), (2, 5), (3, 6), (4, 7), (5, 8)]
a=[1,2,3,4,5,6,7,8]
b=['a','b','c','d']
print list(zip(a,b))#[(1, 'a'), (2, 'b'), (3, 'c'), (4, 'd')]
Supplementary concept:
Sequence: has 4 features
Iteration: Activities that repeat the feedback process, such as for loops, the repeated process is
iterable objects: multiple elements are taken out and used, the iterable object contains the sequence
可迭代对象>序列>元祖,字符串,列表