从 Python 中的列表中提取子列表

Question

how can I extract for example [['A', '123'], ['A', '456']] from mylist if I filtered by 'A'?

mylist = [['A', '123'],
 ['A', '456'],
 ['B','847'],
 ['B','677']]

Answer 1

I made a code for you.

mylist = [['A', '123'],
          ['A', '456'],
          ['B', '847'],
          ['B', '677']]

output = [lst for lst in mylist if 'A' in lst]
print(output)

Or you can use this code;

output = [lst for lst in mylist if 'A' == lst[0]]

Answer 2

Here are two ways to achieve the results you want.

mylist = [['A', '123'],
 ['A', '456'],
 ['B','847'],
 ['B','677']]
letter = 'A'
# Using list comprehension
print([l for l in mylist if l[0] == letter])
# Using filer function 
print(list(filter(lambda l: l[0] == letter, mylist)))