Python 列表限制特定元素到N次

Question

I have a list with 7 items inside like ['S1','S1','S1','S1','L','L','L'] and I want to limit 'L' to be only 2 times and the rest to be 'S1' .

Answer 1

Try it:

lst = ["S1","S1","S1","S1","L","L","L"]

limit = 2
value = "L"

new_lst = []
counter = 0
for i in lst:
    if counter == limit and i == value:
        continue
    if i == value:
        counter += 1
    new_lst.append(i)

print(new_lst)

Answer 2

Using a counter to count the occurrences of L elem in the list and append accordingly:

s = ['S1','S1','S1','S1','L','L','L']

c = 0
res = []
for el in s:
    if el != 'L':
        res.append(el)
    elif c < 2:
        c += 1
        res.append(el)   
print(res)

OUTPUT:

['S1', 'S1', 'S1', 'S1', 'L', 'L']

Edit :

if you want to replace the rest of the L to the S1 :

s = ['S1','S1','S1','S1','L','L','L']

c = 0
res = []
for el in s:
    if el != 'L':
        res.append(el)
    else:
        if c < 2:
            c += 1
            res.append(el)
        else:
            res.append("S1")

print(res)

OUTPUT:

['S1', 'S1', 'S1', 'S1', 'L', 'L', 'S1']