列表理解
当您想要基于现有列表的值创建新列表时，列表理解提供了更短的语法。 （参考-https://www.w3schools.com/python/python_lists_comprehension.asp)
示例：1
方法：1
fruits = ["apple", "banana", "cherry", "kiwi", "mango"]
newlist = []
for x in fruits:
if "a" in x:
newlist.append(x)
print(newlist)
方法：2（综合）
fruits = ["apple", "banana", "cherry", "kiwi", "mango"] newlist = [x for x in fruits if "a" in x] print(newlist)
输出：
['apple', 'banana', 'mango']
示例：2
l = [10,20,30,40]
newlist = []
#using normal loop
for num in l:
newlist.append(num**2)
print(newlist)
#using loop in comprehensive way
newlist = [num**2 for num in l]
print(newlist)
输出：
[100, 400, 900, 1600] [100, 400, 900, 1600]
练习：
1.从2个列表中查找相似的数字以及从相同的2个列表中查找不同的数字。
l1 = [10,20,30,40]
l2 = [30,40,50,60]
得到这个输出：
a) 30,40
#30,40
l1 = [10,20,30,40]
l2 = [30,40,50,60]
#normal method
for num in l1:
for no in l2:
if num== no:
print(num,end=' ')
#comprehensive
print([num for num in l1 for no in l2 if num==no])
输出：
[30, 40]
b) 10,20,50,60
l1 = [10,20,30,40]
l2 = [30,40,50,60]
#comprehensive
output = [num for num in l1 if num not in l2]
output = output + [num for num in l2 if num not in l1]
print(output)
#normal method
for num in l1:
if num not in l2:
print(num,end=' ')
for num in l2:
if num not in l1:
print(num,end=' ')
输出：
[10, 20, 50, 60] 10 20 50 60
2。以综合方法查找给定输出的程序
l1 = [1,2,3]
l2 = [5,6,7]
输出：[(1, 5), (1, 6), (1, 7), (2, 5), (2, 6), (2, 7), (3, 5), (3, 6) , (3, 7)]
l1 = [1,2,3] l2 = [5,6,7] l = [(i,j) for i in l1 for j in l2 if i!=j] print(l)
输出：
[(1, 5), (1, 6), (1, 7), (2, 5), (2, 6), (2, 7), (3, 5), (3, 6), (3, 7)]
3。查找给定输出的程序：
s = "a1b2c3"
输出：abc123
方法：1
s = "a1b2c3"
alpha_list = []
num_list = []
for letter in s:
if letter.isalpha():
alpha_list.append(letter)
else:
num_list.append(letter)
print("".join(alpha_list+num_list))
方法：2
s = "a1b2c3" letter=''.join([i for i in s if i.isalpha()]) no=''.join([i for i in s if i.isdigit()]) print(letter+no)
输出：
abc123
4。查找给定输出的程序：
s = "a4k3b2"
输出：aeknbd
s = "a4k3b2"
i = 0
while i<len(s):
first = s[i]
second = int(s[i+1])
print(first, chr(ord(first)+second),sep='',end='')
i+=2
输出：
aeknbd
说明：
立即学习“Python免费学习笔记（深入）”；
-->使用ord(first)获取first的ascii值，然后将其添加到其中以查找新字符。
-->ord() 用于查找 ascii 值。
-->hr() 转换 ascii 值-->character.
