将每个子列表的第一个元素转换为float

我正在学习，我想找到更有效或更优雅（更短）的方法来做到这一点：

list1 = [['-0.02', 'AAA'], ['-0.20', 'BBB'], ['0.10', 'CCC'], ['0.05', 'DDD']]


def convert_first_element_to_float(lst):
    ls_a = []
    ls_b = []
    for el_a, el_b in lst:
        ls_a.append(float(el_a))
        ls_b.append(el_b)
    return [list(a) for a in zip(ls_a, ls_b)]


result = convert_first_element_to_float(list1)

结果是：

[[-0.02, 'AAA'], [-0.2, 'BBB'], [0.1, 'CCC'], [0.05, 'DDD']]