當您想要基於現有清單的值建立新清單時，清單理解提供了更短的語法。 （參考-https://www.w3schools.com/python/python_lists_compressive.asp）
範例：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（綜合）
fruits = ["apple", "banana", "cherry", "kiwi", "mango"] newlist = [x for x in fruits if "a" in x] print(newlist)
輸出：
['apple', 'banana', 'mango']
範例：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)
輸出：
[100, 400, 900, 1600] [100, 400, 900, 1600]
練習：
1.從2個清單中找出相似的數字以及從相同的2個清單中找出不同的數字。
l1 = [10,20,30,40]
l2 = [30,40,50,60]
得到這個輸出：
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])
輸出：
[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=' ')
輸出：
[10, 20, 50, 60] 10 20 50 60
2。以綜合方法找出給定輸出的程式
l1 = [1,2,3]
l2 = [5,6,7]
輸出：[(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)
輸出：
[(1, 5), (1, 6), (1, 7), (2, 5), (2, 6), (2, 7), (3, 5), (3, 6), (3, 7)]
3。尋找給定輸出的程式：
s = "a1b2c3"
輸出：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)
輸出：
abc123
4。尋找給定輸出的程式：
s = "a4k3b2"
輸出：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
輸出：
aeknbd
說明：
-->使用ord(first)獲得first的ASCII值，然後將其新增至其中以找到新字元。
-->ord() 用來找出 ASCII 值。
-->chr() 轉換 ASCII 值-->字元。
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