日清單理解

列表理解：

這是一種在語法上優雅的方法，可以在一行程式碼中建立或操作清單。

編寫程式列印包含字母「a」的水果（使用for循環）：

fruits = ["apple", "banana", "cherry", "kiwi", "mango"]
newlist = []

for x in fruits:
  if "a" in x:
    newlist.append(x)

print(newlist)

['apple', 'banana', 'mango']

（使用列表理解）：

fruits = ["apple", "banana", "cherry", "kiwi", "mango"]

newlist = [x for x in fruits if "a" in x]
print(newlist)

['apple', 'banana', 'mango']

寫一個程式來計算給定數字的平方根：

l = [10,20,30,40]
newlist = []

#using for 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)

[100, 400, 900, 1600]
[100, 400, 900, 1600]

從 2 個清單中找到相似的號碼以及從相同的 2 個清單中找到不同的號碼：

l1 = [10,20,30,40]
l2 = [30,40,50,60]

#for loop
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])

30 40 
[30, 40]

1 = [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)

#for loop
for num in l1:
    if num not in l2:
        print(num,end=' ')

for num in l2:
    if num not in l1:
        print(num,end=' ')

[10, 20, 50, 60]
10 20 50 60

以綜合方法為給定輸出編寫程式：

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)

[(1, 5), (1, 6), (1, 7), (2, 5), (2, 6), (2, 7), (3, 5), (3, 6), (3, 7)]

為給定的輸出寫一個程式：
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)

abc123

為給定的輸出寫一個程式：

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

aeknbd

任務：

1) 寫一個程式來取得輸出 'abbbbklllbcc'

s = "a4k3b2"
i = 0

while i < len(s):
    first = s[i]  
    second =int(s[i + 1]) 
    print(first,chr(ord(first)+1)*second,sep='',end='')
    i+=2

abbbbklllbcc

2) 寫一個程式來取得輸出 'aaaaakkkkbbb'

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

aaaaakkkkbbb

3.使用綜合 for 和普通 for 迴圈將給定矩陣加入單一清單。

方法：1（使用for迴圈）

matrix = [[10,20,30], [40,50,60], [70,80,90]]
output=[]

for i in matrix:
    for j in i:
        output.append(j)
print(output)

方法：2（使用綜合for循環）

matrix = [[10, 20, 30], [40, 50, 60], [70, 80, 90]]

output = [j for i in matrix for j in i]
print(output)

[10, 20, 30, 40, 50, 60, 70, 80, 90]

4.l = ['ABC','DEF','GHI','JKL']
取得輸出：['ABC', 'def','GHI', 'jkl']

l = ['ABC', 'DEF', 'GHI', 'JKL']

output = [] 
for i, alpha in enumerate(l):
    if i % 2 != 0:
        output.append(alpha.casefold())
    else:
        output.append(alpha)
print(output)

['ABC', 'def', 'GHI', 'jkl']

5.求給定矩陣的行總計：

matrix = [[10,20,30], 
          [40,50,60], 
          [70,80,90]]
for inner in matrix:
    total = 0
    for index,num in enumerate(inner):
        total+=num
    print(total,end=' ')

60 150 240

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