pytorch中.size()
时间: 2024-04-07 21:17:45 浏览: 22
在PyTorch中,`.size()`方法用于获取张量(tensor)的形状(shape)。它返回一个元组,该元组表示张量每个维度的大小。例如,对于一个形状为`(3, 4, 5)`的张量,`.size()`将返回`(3, 4, 5)`。你可以使用`.size(dim)`方法获取指定维度的大小,其中`dim`是一个整数表示维度的索引。例如,对于一个形状为`(3, 4, 5)`的张量,`.size(0)`将返回`3`,`.size(1)`将返回`4`,`.size(2)`将返回`5`。
相关问题
pytorch torch.bmm
`torch.bmm`是PyTorch中的一个函数,用于计算两个tensor的批矩阵乘法。其中,第一个tensor的形状为(*, n, m),第二个tensor的形状为(*, m, p),结果tensor的形状为(*, n, p)。具体来说,对于第一个tensor的第i个矩阵和第二个tensor的第i个矩阵,进行矩阵乘法操作并返回结果tensor中的第i个矩阵。其中,*表示任意的额外维度。
示例代码如下:
```python
import torch
# 创建两个tensor
a = torch.randn(10, 3, 4)
b = torch.randn(10, 4, 5)
# 进行批矩阵乘法操作
c = torch.bmm(a, b)
# 输出结果tensor的形状
print(c.shape) # 输出:torch.Size([10, 3, 5])
```
在这个例子中,a的形状为(10, 3, 4),b的形状为(10, 4, 5),因此结果tensor的形状为(10, 3, 5)。
Pytorch nn.embedding
PyTorch's `nn.Embedding` is a module that allows you to create an embedding layer in your neural network. An embedding layer takes as input a tensor of integer indices, and returns as output a tensor of learnable embeddings corresponding to those indices.
For example, if you have a vocabulary of size `V`, you can create an embedding layer that will map each word in your vocabulary to a `d`-dimensional vector. To do this, you would create an `nn.Embedding` module with input size `V` and output size `d`.
Here is an example of how you can use `nn.Embedding` to create an embedding layer:
```
import torch
import torch.nn as nn
vocab_size = 10000
embedding_dim = 300
input_indices = torch.LongTensor([[1, 4, 6], [2, 3, 0]])
embedding_layer = nn.Embedding(vocab_size, embedding_dim)
embeddings = embedding_layer(input_indices)
```
In this example, we create an embedding layer with input size `vocab_size` (which is 10000 in this case) and output size `embedding_dim` (which is 300 in this case). We then create a tensor `input_indices` with shape `(2, 3)` that contains integer indices corresponding to words in our vocabulary. Finally, we pass `input_indices` through the embedding layer to obtain a tensor `embeddings` with shape `(2, 3, 300)` containing the learned embeddings for each word index.
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