Spacing isn't working according to what I want

[nengwp]

Describe the bug
A clear and concise description of what the bug is.

I wanted to resample my data, but the function didn't work the way I wanted. I'm not sure if it's a bug in the function or if I'm using it incorrectly.

To Reproduce
Steps to reproduce the behavior:

import numpy as np
from monai.transforms import Compose, Spacing,EnsureChannelFirst
from monai.data import MetaTensor

data = np.random.rand(320,320,15)
affine = np.array(
    [
        [0.62499992083390921,0.0003145752807000713,-1.1700334066756456e-11,0],
        [8.2218805437499005e-06,-0.0163353013234998,-0.62478648982117957,0],
        [-0.0012075562252165173,2.39917943568003,-0.062727555057372444,0],
        [0,0,0,1]
    ]
)

# metadata spcaing about (0.625 0.625 2.4)

metadata = MetaTensor(data,affine=affine)
respacing = Compose([EnsureChannelFirst(),Spacing(pixdim=[0.3,0.3,2])])

remetadata = respacing(metadata)
print(remetadata.shape)

# (1, 670, 2555, 5)  why 2555? and why 5?
# I want about (1,670,670,18) but it's not.

Expected behavior
A clear and concise description of what you expected to happen.

I expect the shape to scale from [0.65 0.65 2.4] to [0.3 0.3 2].

Screenshots
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Environment

================================
Printing MONAI config...
================================
MONAI version: 1.0.1
Numpy version: 1.21.6
Pytorch version: 1.12.1
MONAI flags: HAS_EXT = False, USE_COMPILED = False, USE_META_DICT = False
MONAI rev id: 8271a193229fe4437026185e218d5b06f7c8ce69
MONAI __file__: /home/nengwp/miniconda/lib/python3.7/site-packages/monai/__init__.py

Optional dependencies:
Pytorch Ignite version: 0.4.9
Nibabel version: 4.0.2
scikit-image version: 0.19.3
Pillow version: 9.0.1
Tensorboard version: 2.11.0
gdown version: 4.5.1
TorchVision version: 0.13.1
tqdm version: 4.64.1
lmdb version: 1.3.0
psutil version: 5.9.0
pandas version: 1.3.5
einops version: 0.4.1
transformers version: NOT INSTALLED or UNKNOWN VERSION.
mlflow version: 1.28.0
pynrrd version: 0.4.3

================================
Printing system config...
================================
System: Linux
Linux version: Ubuntu 20.04.1 LTS
Platform: Linux-5.8.0-49-generic-x86_64-with-debian-bullseye-sid
Processor: x86_64
Machine: x86_64
Python version: 3.7.6
Process name: python

Additional context
Add any other context about the problem here.

[wyli]

based on that affine, the initial spacing is actually computed as (0.6250, 2.3992, 0.6279) instead of (0.625 0.625 2.4):

metadata = MetaTensor(data, affine=affine)
print(metadata.pixdim)
# tensor([0.6250, 2.3992, 0.6279], dtype=torch.float64)