TypeError: slice indices must be integers or None or have an index method in python 2.7

Question

for file in zip(frames_list[-round(0.2 * len(frames_list)):], masks_list[-round(0.2 * len(masks_list)):]):
    # Convert tensors to numpy arrays
    frame = frame_batches.next().numpy().astype(np.uint8)
    mask = mask_batches.next().numpy().astype(np.uint8)

    # Convert numpy arrays to images
    frame = Image.fromarray(frame)
    mask = Image.fromarray(mask)

    # Save frames and masks to correct directories
    frame.save(DATA_PATH + '{}_frames/{}'.format(dir_name, dir_name) + '/' + file[0])
    mask.save(DATA_PATH + '{}_masks/{}'.format(dir_name, dir_name) + '/' + file[1])

print("Saved {} frames to directory {}".format(len(frames_list), DATA_PATH))
print("Saved {} masks to directory {}".format(len(masks_list), DATA_PATH))

回溯

Traceback (most recent call last):
  File "/home/khawar/Desktop/Khawar_Seg/main.py", line 190, in <module>
    generate_image_folder_structure(frame_tensors, masks_tensors, frames_list, masks_list)
  File "/home/khawar/Desktop/Khawar_Seg/main.py", line 173, in generate_image_folder_structure
    for file in zip(frames_list[-round(0.2 * len(frames_list)):], masks_list[-round(0.2 * len(masks_list)):]):
TypeError: slice indices must be integers or None or have an __index__ method

Answer 1

python 2.7 returns 中的 round 函数是 float 类型，但序列切片需要 int 作为参数。

>>> type(round(2.0))
<type 'float'>

>>> items = [0, 1, 2, 3, 4]
>>> items[round(2.0):]
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: slice indices must be integers or None or have an __index__ method

# If we cast the rounded index to an int, it will work
>>> index = int(round(2.0))
>>> type(index)
<type 'int'>

>>> items[int(round(2.0)):]
[2, 3, 4]

因此，对于您的示例代码，您需要先将索引转换为整数，然后再在切片中使用它们——for 循环的 [<start>:<end>] 部分。

frames_index = -int(round(0.2 * len(frames_list)))
masks_index = -int(round(0.2 * len(masks_list)))

for file in zip(frames_list[frames_index:], masks_list[masks_index:]):
    ...

为了更容易阅读，我建议你使用一个函数来制作你的索引号：

def get_list_index(list_size):  # list_size is the len(<list>)
    float_value = round(0.2 * list_size)
    return -int(float_value)

frames_index = get_list_index(len(frames_list))
masks_index = get_list_index(len(masks_list))

for file in zip(frames_list[frames_index:], masks_list[masks_index:]):
    ...

编辑：

回答您评论中的问题：

what is the meaning of : in for file in zip(frames_list[-round(0.2 * len(frames_list)):]?

: 将 start 索引与 end 索引分开 python 切片表示法。

例如，如果您有列表 ['a', 'b', 'c', 'd', 'e'] 并且您只想获取从 'b' 到 'd' 的部分，您将使用从 [=26= 开始的切片] 并以 4 结束——比 'd' 的索引多 _1。

>>> ['a', 'b', 'c', 'd', 'e'][1:4]
['b', 'c', 'd']

Python 允许您使用 negative 索引，因此您可以从右侧倒数。我们可以使用 -1 而不是 3:

来编写相同的切片

>>> ['a', 'b', 'c', 'd', 'e'][1:-1]
['b', 'c', 'd']

如果我们想要 all 列表中的项目，从 'b' 开始到最后，我们可以将我们的右索引更改为 None 或将其省略：

>>> ['a', 'b', 'c', 'd', 'e'][1:None]
['b', 'c', 'd', 'e']

>>> ['a', 'b', 'c', 'd', 'e'][1:]
['b', 'c', 'd', 'e']

TypeError: slice indices must be integers or None or have an index method in python 2.7

TypeError: slice indices must be integers or None or have an index method in python 2.7

python-2.7

tensorflow

tensorflow2.0

TypeError: slice indices must be integers or None or have an __index__ method in python 2.7

TypeError: slice indices must be integers or None or have an __index__ method in python 2.7

python-2.7

tensorflow

tensorflow2.0

TypeError: slice indices must be integers or None or have an index method in python 2.7

TypeError: slice indices must be integers or None or have an index method in python 2.7