python tuple、list相关

#python list
‘‘‘
创建list有很多方法：

1.使用一对方括号创建一个空的list：[]
2.使用一对方括号，用‘,‘隔开里面的元素：[a, b, c], [a]
3.Using a list comprehension:[x for x in iterable]
4.Using the type constructor:list() or list(iterable)

‘‘‘

def create_empty_list():
‘‘‘Using a pair of square brackets to denote the empty list: [].‘‘‘
return []

def create_common_list():
‘‘‘Using square brackets, separating items with commas: [a], [a, b, c].‘‘‘
return [‘a‘, ‘b‘, ‘c‘, 1, 3, 5]

def create_common_list2():
‘‘‘Using a list comprehension: [x for x in iterable].‘‘‘
return [x for x in range(1, 10)]

def str_to_list(s):
‘‘‘Using a string to convert list‘‘‘
if s != None:
return list(s)
else:
return []

def main():
test_listA = create_empty_list()
print(test_listA)
print(‘#‘ * 50)
test_listB = create_common_list()
print(test_listB)
print(‘#‘ * 50)
test_listC = create_common_list2()
print(test_listC)
print(‘#‘ * 50)
test_str = ‘i want to talk about this problem!‘
test_listD = str_to_list(test_str)
print(test_listD)

if __name__ == ‘__main__‘:
main()

2、tuple 转 list

#!/usr/bin/env python
# -*- coding:utf-8 -*-

aTuple=(12,3,‘a‘,‘yy‘)
aList=list(aTuple)
print "aTyple type is: ",type(aTuple)
print "aList type is: ",type(aList)
print "aList‘s value is: ",aList

运行结果

[[email protected] 20170120]# python tuple2list.py
aTyple type is:  <type ‘tuple‘>
aList type is:  <type ‘list‘>
aList‘s value is:  [12, 3, ‘a‘, ‘yy‘]

3、tuple与list相似，但是tuple不能修改，tuple使用小括号，列表用方括号

tuple创建，只需在括号中添加元素，并使用逗号隔开即可

tuple创建只包含一个元素时，需在元素后面添加逗号

tup1=(50,)

1 >>> tup1 = ("all")
2 >>> print tup1
3 all
4 输出字符串 all，这是因为括号()既可以表示tuple，又可以表示数学公式中的小括号。
5 所以，如果元组只有1个元素，就必须加一个逗号，防止被当作括号运算：
6 >>> tup1 = ("all",)
7 >>> print tup1
8 (‘all‘,)
9 >>> 

[[email protected] 20170120]# cat tuple.py
#!/usr/bin/env python
# -*- coding:utf-8 -*-

tup1=(‘physics‘,‘chemistry‘,1997,2000);
tup2=(1,2,3,4,5,6,7,8,9);

print "tup1[0]:",tup1[0];
print "tup2[1:5]:",tup2[1:5];
[[email protected] 20170120]# python tuple.py
tup1[0]: physics
tup2[1:5]: (2, 3, 4, 5)

修改元组

元组中的元素不能修改，但可以对元组进行连接组合

#代码
#!/usr/bin/env python
# -*- coding:utf-8 -*-

tup1=(12,34.56)
tup2=(‘abc‘,‘xyz‘)

tup3=tup1+tup2
print tup3

#运行结果
[[email protected] 20170120]# python tuple.py
(12, 34.560000000000002, ‘abc‘, ‘xyz‘)

删除元组

#!/usr/bin/env python
# -*- coding:utf-8 -*-

tup1=(‘physics‘,‘chemistry‘,1997,2000);
print tup1
del tup1
print "After deleting tup1:"
print tup1

#执行结果
[[email protected] 20170120]# python tuple.py
(‘physics‘, ‘chemistry‘, 1997, 2000)
After deleting tup1:
Traceback (most recent call last):
  File "tuple.py", line 8, in <module>
    print tup1
NameError: name ‘tup1‘ is not defined