Thanks too,
I have find the answer from
"https://stackoverflow.com/questions/772124/what-does-the-python-ellipsis-object-do";
This came up in another question recently. I'll elaborate on my answer from
there:
Ellipsis is an object that can appear in slice notation. For example:
myList[1:2, ..., 0]
Its interpretation is purely up to whatever implements the __getitem__ function
and sees Ellipsis objects there, but its main (and intended) use is in the
numeric python extension, which adds a multidimensional array type. Since there
are more than one dimensions, slicing becomes more complex than just a start
and stop index; it is useful to be able to slice in multiple dimensions as
well. E.g., given a 4x4 array, the top left area would be defined by the slice
[:2,:2]:
>>> a
array([[ 1, 2, 3, 4],
[ 5, 6, 7, 8],
[ 9, 10, 11, 12],
[13, 14, 15, 16]])
>>> a[:2,:2] # top left
array([[1, 2],
[5, 6]])
Extending this further, Ellipsis is used here to indicate a placeholder for the
rest of the array dimensions not specified. Think of it as indicating the full
slice [:] for all the dimensions in the gap it is placed, so for a 3d array,
a[...,0] is the same as a[:,:,0] and for 4d, a[:,:,:,0], similarly, a[0,...,0]
is a[0,:,:,0] (with however many colons in the middle make up the full number
of dimensions in the array).
Interestingly, in python3, the Ellipsis literal (...) is usable outside the
slice syntax, so you can actually write:
>>> ...
Ellipsis
Other than the various numeric types, no, I don't think it's used. As far as
I'm aware, it was added purely for numpy use and has no core support other than
providing the object and corresponding syntax. The object being there didn't
require this, but the literal "..." support for slices did.
在 2019-10-26 22:51:31，"xuanwu348" <[email protected]> 写道：
Hi buddies
Have a good weekend!
I have read some code in caffe, but I confused at "net.blobs['data'].data[...]
= transformed_image".
The code can be find in this
link:https://github.com/BVLC/caffe/blob/master/examples/00-classification.ipynb
import caffe
model_def = os.path.join(caffe_root, "models/bvlc_alexnet/deploy.prototxt")
model_weights = os.path.join(caffe_root,
"models/bvlc_alexnet/bvlc_alexnet.caffemodel")
net = caffe.Net(model_def,
model_weights,
caffe.TEST)
net.blobs['data'].reshape(50,
3,
227,227)
net.blobs['data'].data[...] = transformed_image
1. For ellipsis, is there syntax in python like this "
net.blobs['data'].data[...]"? I have checked it which the type is "<class
'numpy.ndarray'>"
2. Could you provide some samples in which need to use ellipsis.
But in python, ellipsis define as below, I did not find the relationship to
"net.blobs['data'].data[...]":
Help on ellipsis object:
class ellipsis(object)
| Methods defined here:
|
| __getattribute__(self, name, /)
| Return getattr(self, name).
|
| __new__(*args, **kwargs) from builtins.type
| Create and return a new object. See help(type) for accurate signature.
|
| __reduce__(...)
| helper for pickle
|
| __repr__(self, /)
| Return repr(self).
Thanks for your help!
Best Regards
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