fix bug of loading_txt(map doesn't return a list or tuple actually)

[cqbu]

Map function doesn't return a list or a tuple actually, so we need use list or tuple before map.
For example, we need use np.array(list(map(float, data[1:5]))) or np.array(tuple(map(float, data[1:5]))) instead of np.array(map(float, data[1:5])).
And here I use list, you can also use tuple. I find nerfstudio use tuple actually. Anyway, we cannot use map only when we use list as a input.