如何使用python比較列表中的元素並檢查第一個列表元素是否包含在另一個列表的元素中

Question

我有兩個列表l1和l2包含像

l1 = ['a','b','c','d']
l2 = ['a is greater', 'f is greater', 'c is greater']

我想比較 l1 的元素並查找 l2 是否包含在它們的元素中。 願望輸出將是

f is greater

按照我試過的代碼，

for i in l2:
    for j in l2:
    if j not in l1:
        print(i)

但我觀察到的輸出是

a is greater
a is greater
f is greater
f is greater
c is greater
c is greater

請幫助我了解我需要添加什么才能獲得適當的輸出。 謝謝。

Answer 1

用：

l1 = ['a','b','c','d']
l2 = ['a is greater', 'f is greater', 'c is greater']

# iterate over the elements of l2
for i in l2:

    # check if the first letter of e is in l1
    if i[0] not in l1:
        print(i)

輸出

f is greater

您不需要對l2的元素迭代兩次，並檢查值 ( i[0] ) 是否在集合 ( l1 ) 中使用in 。

更新

如果您想檢查不同的位置，只需更改 i 上的索引，例如，如果您想檢查最后一個位置，請執行以下操作：

l1 = ['a','b','c','d']
l2 = ['Greater is c', 'Greater is f', 'Greater is d']

# iterate over the elements of l2
for i in l2:

    # check if the first letter of e is in l1
    if i[-1] not in l1:  # note the -1
        print(i)

輸出

Greater is f

如果您想考慮l1中不存在句子中的所有單詞（由空格分隔），一種方法：

l1 = ['a', 'b', 'c', 'd']
l2 = ['Greater is c', 'Greater is f', 'f is greater', "Hello a cat"]

s1 = set(l1)

# iterate over the elements of l2
for i in l2:

    # check if the first letter of e is in l1
    if s1.isdisjoint(i.split()):
        print(i) 

輸出

Greater is f
f is greater

如果檢查字符串包含，請執行以下操作：

l1 = ['Book Date:', 'Statement Number:', 'Opening Book Balance:', 'Closing Book Balance:', 'Number Of Debits:',
      'Number of Credits:', 'Total Debits:', 'Total Credits:', 'Report Date:', 'Created by:', 'Modified by:', 'Printed by:']
l2 = ['<p>Book Date: 06-01-21 To 06-30-21</p>', '<p>Statement Number: 126 </p>', '<p>this value need to print</p>']


# iterate over the elements of l2
for i in l2:

    # check if the first letter of e is in l1
    if not any(j in i for j in l1):
        print(i)

輸出

<p>this value need to print</p>

Answer 2

干得好：

ref = ('a','b','c','d')
l2 = ['a is greater', 'f is greater', 'c is greater']
l3 = ['Greater is c', 'Greater is f', 'Greater is d']
l4 = ['...c...', '...f...', '...d...']

[item for item in l2 if not item.startswith(ref)] # 'f is greater'
[item for item in l3 if not item.endswith(ref)]   # 'Greater is f'
[item for item in l4 if not any(letter in item for letter in ref)] # '...f...'