如何获得清单清单？

Question

I have a problem like that:

list = ['a1',['b1',2],['c1',2,3],['d1',2,3,4]]

I want to get a new list like that

new_list['a1','b1','c1','d1']

I do like this:

lst = ['a1',['b1',2],['c1',2,3],['d1',2,3,4]]
for item in lst:
   print(item)

result is:

a1
['b1', 2]
['c1', 2, 3]
['d1', 2, 3, 4]

But I want the first element of each result

The best answer is like this :

my_list = list()
lst = ['a1',['b1',2],['c1',2,3],['d1',2,3,4]]
for element in lst:
if type(element)==type('string'):
    my_list.append(element)
else:
    my_list.append(element[0])
print(my_list)

Thank you!

Answer 1

Do it as below:

>>> my_list = list()
>>> lst = ['a1',['b1',2],['c1',2,3],['d1',2,3,4]]
>>> for element in lst:
    if type(element)==type('string'):
        my_list.append(element)
    else:
        my_list.append(element[0])

It will produce:

>>> my_list
['a1', 'b1', 'c1', 'd1']
>>> 

As you see above, first I created a list (named my_list ) and then checked each elements of your list. If the element was a string, I added it to my_list and otherwise (ie it is a list) I added the first element of it to my_list .

Answer 2

I would do

res = []
for x in the_list:
    if x is Array:
        res.append(x[0])
    else:
        res.append(x)