li = ['alex','eric','Roman']
for i in enumerate(li,10):
print (i)

结果:

   (10, 'alex')
  (11, 'eric')
  (12, 'Roman')

 结论: enumerate方便给元素添加一个自增的序号

print (ord('c'))
print (chr(99))
结果:

  99
  c

 结论:ord可以将字符转为ascii码,chr可以将ascii转为字符串

 

a1 = "[[1,2], [3,4], [5,6], [7,8], [9,0]]"
b1 = eval(a1)
print (b1)
print (type(b1))
结果:

  [[1, 2], [3, 4], [5, 6], [7, 8], [9, 0]]
  <class 'list'>

 结论:字符串转换为列表


a2 = "([1,2], [3,4], [5,6], [7,8], [9,0])"
b2 = eval(a2)
print (b2)
print (type(b2))
结果:

  ([1, 2], [3, 4], [5, 6], [7, 8], [9, 0])
  <class 'tuple'>

 结论:字符串转换为元祖


a3 = "{1:'a',2:'b',3:'c'}"
b3 = eval(a3)
print (a3)
print (type(b3))
结果:

  {1:'a',2:'b',3:'c'}
  <class 'dict'>

 结论:字符串转化为字典

li = [11,22,33,44]
# new_li = list(map(lambda x:x+100,li))
# print(type(new_li))
# print (new_li)

def func(x):
x = x+100
return x
new_li = list(map(func,li))
print (new_li)
结果:[111, 122, 133, 144]
结论:map函数将输入进行处理到输出,一对一的操作,map第一个参数为函数

li = [11,22,33,44]
def func(x):
if x>22:
return True
else:
return False
f_li = list(filter(func,li))
print (f_li
结果:[33, 44]
结论:通过filter函数可以通过函数来进行过滤操作


posted on 2016-05-02 00:40  Alex0425  阅读(250)  评论(0编辑  收藏  举报