Permute 2 2 5 6
Permute 2 2 5 90 Degree; Permute 2 2 5 90; Permute 2 2 5 95; But q and e could be together as eq. Therefore, the total number of ways they can be next to each other is 2 5! Permutations of less than all. We have seen that the number of ways of choosing 2 letters from 4 is 4 3 = 12. Ltd., Jaipur, Rajasthan. 531 likes 15 were here. We offer Website Designing, Custom Software Development and Web Application Development, including Offshore Software Development model. Covers permutations with repetitions. We have moved all content for this concept to for better organization. Please update your bookmarks accordingly. C) permutation of the triple 5,5,1: P 2,1.(3) = 3 d) permutation of the triple 5,4,2: P(3) = 3! = 6 e) permutation of the triple 5,3,3: P. 1,2 (3) = 3. In mathematics, particularly in matrix theory, a permutation matrix is a square binary matrix that has exactly one entry of 1 in each row and each column and 0s elsewhere. Each such matrix, say P, represents a permutation of m elements and, when used to multiply another matrix, say A, results in permuting the rows (when pre-multiplying, to form PA) or columns (when post.
PyTorch provides a lot of methods for the Tensor type. Some of these methodsmay be confusing for new users. Here, I would like to talk aboutview()
vsreshape()
,transpose()
vspermute()
.
view() vs transpose()
Both view()
and reshape()
can be used to change the size or shape oftensors. But they are slightly different.
The view()
has existed for a long time. It will return a tensor with the newshape. The returned tensor shares the underling data with the original tensor.If you change the tensor value in the returned tensor, the corresponding valuein the viewed tensor also changes.
On the other hand, it seems that reshape()
has been introduced in version0.4. According to thedocument, thismethod will
Returns a tensor with the same data and number of elements as input, but with the specified shape. When possible, the returned tensor will be a view of input. Otherwise, it will be a copy. Contiguous inputs and inputs with compatible strides can be reshaped without copying, but you should not depend on the copying vs. viewing behavior.
It means that torch.reshape
may return a copy or a view of the originaltensor. You can not count on that to return a view or a copy. According to thedeveloper:
if you need a copy use clone() if you need the same storage use view(). The semantics of reshape() are that it may or may not share the storage and you don’t know beforehand.
As a side note, I found that torch version 0.4.1 and 1.0.1 behaves differentlywhen you print the id
of original tensor and viewing tensor:
You see that id
of a.storage()
and b.storage()
is not the same. Isn’tthat their underlying data the same? Why this difference?
I filed an issue in thePyTorch repo and got answers from the developer. It turns out that to find thedata pointer, we have to use the data_ptr()
method. You will find that theirdata pointers are the same.
view() vs transpose()
transpose()
, like view()
can also be used to change the shape of a tensorand it also returns a new tensor sharing the data with the original tensor:
Permute 2 2 5 6 2 Loader
Returns a tensor that is a transposed version of input. The given dimensions dim0 and dim1 are swapped.
The resulting out tensor shares it’s underlying storage with the input tensor, so changing the content of one would change the content of the other.
One difference is that view()
can only operate on contiguous tensor and thereturned tensor is still contiguous. transpose()
can operate both oncontiguous and non-contiguous tensor. Unlike view()
, the returned tensor maybe not contiguous any more.
But what does contiguous mean?
Permute 2 2 5 6 2
There is a good answer on SOwhich discusses the meaning of contiguous
in Numpy. It also applies toPyTorch.
As I understand, contiguous
in PyTorch means if the neighboring elements inthe tensor are actually next to each other in memory. Let’s take a simpleexample:
Tensor x
and y
in the above example share the same memory space1.
If you check their contiguity withis_contiguous()
,you will find that x
is contiguous but y
is not.
Since x is contiguous, x[0][0] and x[0][1] are next to each other in memory.But y[0][0] and y[0][1] is not.
A lot of tensor operations requires that the tensor should be contiguous,otherwise, an error will be thrown. To make a non-contiguous tensor becomecontiguous, use call thecontiguous()
,which will return a new contiguous tensor. In plain words, it will create a newmemory space for the new tensor and copy the value from the non-contiguoustensor to the new tensor.
permute()
and tranpose()
are similar. transpose()
can only swap twodimension. But permute()
can swap all the dimensions. For example:
2+2=5 Lyrics
Note that, in permute()
, you must provide the new order of all thedimensions. In transpose()
, you can only provide two dimensions. tranpose()
can be thought as a special case of permute()
method in for 2D tensors.
- tensor data pointers.
- view after transpose raises non-contiguous error.
- When to use which, permute, view, transpose.
- Difference between reshape() and view().
Permute 2 2 5 6 1/2
To show a tensor’s memory address, use
tensor.data_ptr()
. ↩︎