Pytorch index tensor with tensor. Whats new in PyTorch tutorials.

Pytorch index tensor with tensor. So I want something like in each batch, for each token in a sequence, return the probability of a particular class. 3], [-0. rand((10, 1000, 96)) and an array(or tensor) of actual lengths for each sentence lengths = torch . Can be a list, tuple, NumPy ndarray, scalar, and other types. tensor(idx_list) # indexing and splitting list_of_tensors = tensor[:, idx_tensor, :]. 3, -0. index_select(x, 0, torch. Parameters Tensor. , 652. keep the unique value from the previous positions if the current position is following a 2 started sequence. 0500, 0. item()-your_tensor))<0. 0600]) idxs = torch. Mar 11, 2021 · My solution for now is: x = torch. I can do this by creating row and column index tensors, selecting from the input tensor, and then reshaping, but is there a more efficient way to do Jun 9, 2019 · The torch. shape=[b, n], s. dtype (torch. g. So I want to create a mask using the length of sentence data in the batch. index_select(input, dim, index, *, out=None) → Tensor. torch. Whats new in PyTorch tutorials. 1 and -0. , 566. tensor ( [ [0,2,1], [2,3,0]]) # How to do it in batch ? c_1 = a [0] [idx [0]]. Is there a proper approach to do this ? (I also checked some tutorial on tensor indexing e. Transformer. I have a value tensor C of shape [b] I want to assign values such that A[i,j,B[i,j]] = C[j]. data (array_like) – Initial data for the tensor. Here is an example: Input: [2, 0, 0, 2, 1, 0, 0, 2, 1, 1, 0 Run PyTorch locally or get started quickly with one of the supported cloud platforms. Oct 29, 2024 · The torch. nonzero()) Here I want to get the index of max_value in the float tensor, you can also put your value like this to get the index of any elements in tensor. split:. tensor([[1, 2, 3], [4, 5, 6]]) # Create the index tensor. cat ( (c_1, c_2), dim=0) The desired output is: tensor ( [ [1, 3, 2], [7, 8, 5]]) I tried a [idx], however, it goes wrong. After some trial and error, I found that the following does what I want: result = x[i[:, 0], i[:, 1], i[:, 2]] I was wondering if there was a better way to do so. Which class probability to return will be Run PyTorch locally or get started quickly with one of the supported cloud platforms. gather(): import torch. I tried this, however it selects each index in indices for each first dimension in sequences instead of only one. Intro to PyTorch - YouTube Series May 12, 2022 · Hi! I have a 4D tensor A with shape (B, X, Y, Z) and a tensor B with shape (N, 4), each of whose rows stores the index of one element of tensor A. Why were the results of the two assignments different? May 15, 2022 · Hi guys, I am trying to implement a function that generates unique indexes for a tensor. Jul 19, 2021 · Suppose i have a 2d index Array of shape [B,1,N,2] i. What you can do is to apply your condition and get a binary mask of indices that match the condition and find the indices using torch. view(3,3,3,3) >> b = torch. I tried direct indexing but that does not work with multidimensional indexes. , 545. Tensor. So the rows of idx look like: Sep 12, 2018 · This is probably a very basic question but i’m having a hard time finding a solution. ones((2, 4)) [[1, 1, 1, 1], [1, 1, 1, 1]] and want to fill two positions per row with 0, to get: [[1, 0, 1, 0], [0, 1 I have the following torch tensor: tensor([[-0. For example: G = tensor([1, 4, 9]) X = tensor([[2, 3, 7, 9], [8, 6, 7, 5]]) For every element in X, I want to find the index of the nearest element in G (minimum distance) as follows: Sep 23, 2020 · I’m trying to create *_key_padding_mask for torch. It efficiently selects elements from a tensor based on indices. I need this to be differentiable, and ideally with only pure torch operations and without loops. I have a 4D input tensor of size (1,200,61,1632), where 1632 is the time dimension. Learn the Basics. When the output tensor of an arithmetic operation is specified, we allow casting to its dtype except that: An integral output tensor cannot accept a floating point tensor. zeros(2, 3) a. e. tensor([1, 1])], torch. , 576. I want as output a 2d tensor with the same number of rows as the input tensor and cols as the index tensor. tensor(1, 0), torch. Intro to PyTorch - YouTube Series Tensor. rand(12, 512, 768) # create tensor with idx idx_list = [0,2,3,400,5,32,7,8,321,107,100,511] # convert list to tensor idx_tensor = torch. In the previous post, we learned about one-dimensional tensors in PyTorch and applied some useful tensor operations. ,1000. index_select, but they Apr 8, 2023 · Using the PyTorch framework, this two-dimensional image or matrix can be converted to a two-dimensional tensor. Dec 2, 2020 · a = torch. I tried using a for loop but it’s too slow. The returned tensor has the same number of dimensions as the original tensor (input). dtype, optional) – the desired data type of returned tensor. I also tried gather but it does not work because the index and the souc&hellip; Dec 8, 2018 · So first let me describe my use case. , 803. randint(1000,(10,)) outputs tensor([ 370. Nov 1, 2021 · Here are some other types of None indexings. Apr 4, 2024 · I have an index tensor like we send input to a bert model after tokenization, so the shape is [batch_size, seq_len] and I have to return a tensor with 0’s and 1’s (1’s where the indices are matched) of shape [batch_size, seq_len, vocab_size]. Thus, the function would return a 1D tensor of N elements. 1 and I have a question about making mask tensor using index tensor. IntTensor([1,3,2,1,4,2]) b=[2,1,6] I want to find index of values in list b, with the result index sorted like output as tensor([0, 2, 3, 5]) Jul 23, 2023 · index: a 1-D tensor containing the indices of the dimensions that you want to select. I have a tensor of shape NxCxseq_len. If you want to insert a dimension on dim=2, you can add a second : as n[:, :, None]. For example 0. Assuming number of time steps t=7 t=8 Edit: changed value of t batch_size =&hellip; I have: inp = torch. view (1,-1) c = torch. 3. I want to index it with a tensor idx which is size (4,1632) where each row of idx is a value I want to extract from the input tensor. In particular, I have tensor A of shape [a,b,c] and index tensor B of shape [a,b]. I would like to extract the x values at these indices. sum Jul 27, 2024 · view()とunsqueeze()は、PyTorchでTensorの形状を変更するために使用される関数です。それぞれの機能unsqueeze() Tensorに新しい次元を追加します。 新しい次元は、指定された軸に挿入されます。 元のTensorのデータは変更されません。 Oct 21, 2019 · Let’s say I have a tensor A of shape (BatchxDim1xDim2x…) and a tensor B of shape (Batch) B = Tensor([1,3,7,2,…]) that encodes indices that I am interested in. here and Aug 25, 2018 · I need to sort a 2D tensor and apply the same sorting to a 3D tensor. The resulting expression selects the elements from each row of the main_tensor using the corresponding index from the squeezed index_tensor. Tensor([[0, 0, 0, 0], [0, 0, 0, 1]]) # I want to access tensor A: A[0, 0, 0, 0] = 1 A[0, 0, 0, 1] = 1 How can I access tensor A using tensor B without for loop? I find it difficult to use scatter, index_select, and index_put May 13, 2020 · Hi, I used pytorch 1. Out Random Tensors and Seeding¶. , 859. In the example above : is was used as a placeholder to designate the first dimension dim=0. Out-of-place version of torch. Both slicing and logical indexing are possible, but are Feb 9, 2022 · I have a problem where I want to find the nearest indices of a nested tensor based on a flat tensor having arbitrary dimensions. Sep 21, 2019 · I have a 4D tensor x, and a 2D index tensor i of shape (N, 3), where i[n] is an index over the first 3 dimensions of x. 1], [-0. gather() function is the primary tool for this task. tensor Mar 2, 2021 · Hello everyone! I’m trying to implement the following function as efficiently as possible: Given I have a sorted 1D tensor of positive integers, I want to retrieve the index of the first occurrence of each value. I want to have a tensor of shape (x), where each the ith element is T[i, L[i]]. index_copy. The result slice tensor will have dimension (x,y) or (x,y,1). Bite-size, ready-to-deploy PyTorch code examples. t. I want the columns that correspond to a 1 value in the index vector. ]) How to fill tensor ‘a’ with zeros after certain index along dimension 1 (sentence length) according to tensor ‘lengths Apr 5, 2019 · There is also a way just using PyTorch and avoiding the loop using indexing and torch. In each element of idx there is an integer between 0 and N. index_fill. index_select和gather pytorch说明: index_select; gather. For example: B = torch. Nov 17, 2018 · I have a tensor T of shape (x, y) and a list L of shape (x), containing numbers [0, y). index_copy_ (dim, index, tensor) → Tensor ¶ Copies the elements of tensor into the self tensor by selecting the indices in the order given in index . It seems very simple and almost like masked_fill_, but my index tensor doesn’t have the same size as the data tensor. Casting Examples: Apr 10, 2020 · Hello, I have a 3D tensor A of size (x,y,z) and an 1D vector B of size (y), in which each (index,value) in B correspond to a pair of index of y-dimension and z-dimension. 0300, 0. Can you please take a quick look at it? I am looking for something like x. Is there an efficient way of doing this better Lets say I have a tensor of size [100, 100] and I have a set of start_indices and end_indices of size [100] I want to be able to do something like this: tensor[start_indices:end_indices, :] = 0 Aug 18, 2019 · Given a 3d tenzor, say: batch x sentence length x embedding dim a = torch. tensor = torch. index_fill_(index, 42) in the following example: Jul 18, 2021 · PyTorch is a python library developed by Facebook to run and train deep learning and machine learning algorithms. A boolean output tensor cannot accept a non-boolean tensor. stack([value[i, index[i] ]for i in range(len(value))]) Dec 6, 2022 · I have a 2d input tensor and a 2d index tensor with the same number of rows where each value represents the column index I want to select. , 502. Intro to PyTorch - YouTube Series Jul 8, 2020 · I have a data tensor and an index tensor: d = torch. Loop-Based Approach Sep 7, 2021 · I am new to PyTorch and am still wrapping my head around how to form a proper gather statement. 2, 0. I want the numpy array to index each sub-element of my tensor. Mar 28, 2022 · For floating point tensors, I use this to get the index of the element in the tensor. arange(3*3*3*3). tensor([0, 2])) to select the first and third rows of x and return a new tensor of shape (2, 4) like this: Dec 17, 2018 · I have a Tensor X of the shape B x N x D, a Batch of vectors of N points in D-Dimensional space. For example, if dim == 0 and index[i] == j , then the i th row of tensor is copied to the j th row of self . 2]) i. index_select(input, dim, index) Returns a new tensor which indexes the input tensor along dimension dim using the entries in index which is a LongTensor. manual_seed() immediately preceding it? Initializing tensors, such as a model’s learning weights, with random values is common but there are times - especially in research settings - where you’ll want some assurance of the reproducibility of your results. I know this can be done for a single value, for example index 1: torch. Suppose I have a tensor of size 100 * 5 * 3 (batch_size * seq_len * distinct_class_probs) I need to index dim=2 (distinct_class_probs) with a tensor. index_fill_ (dim, index, value) → Tensor ¶ Fills the elements of the self tensor with value value by selecting the indices in the order given in index . index_copy_(). What is the best way to obtain a tensor C such that C[i,j… Feb 16, 2022 · I have a value tensor value. nonzero(). The rules are simple: assign a new unique value for each position that value equals to 2. 2]]) and the following numpy array: (I can convert it to something else if necessary) [1 0 1] I want to get the following tensor: tensor([0. I have an index tensor of shape NxK (basically K from each batch) where K denotes the indices from the seq_len axis and I need to pick these specific samples. , 964. I want to index X using idx such that I get a Tensor of the shape B x N x K x D. Here's a breakdown of how to use torch. Given a = torch. randrange(n_classes) for _ in range(n_samples)] # Convert to torch Tensor labels_tensor = torch. Returns a new tensor which indexes the input tensor along dimension dim using the entries in index which is a LongTensor. Nov 1, 2022 · When you index into a tensor, you are plucking out values from unstructured locations, so you would need a more complicated view / access approach, and pytorch prefers the efficiency that making a copy provides for any future manipulations of the tensor. 4, 0. Is there a fast way in Pytorch so that I can get the index that can be used to slice the tensor? Thanks a lot! Parameters. index的shape本来是(2,2), 里面的每个value被expand成了一个(3,4)的tensor, 故最后结果为shape为(2,2,3,4)的tensor. index_put([torch. May 31, 2019 · a = torch. The expression tensor. I looked at torch. Is this possible? In Tensorflow, I would use tf. A non-complex output tensor cannot accept a complex tensor. (Pytorch does not try to be clever enough to recognize whether the result Nov 9, 2020 · if I have a 2D tensor like this one: >>> torch. split(1, dim=1) Mar 23, 2020 · I defined four tensors that represent index_x,index_y,index_z,and value,respectively and assigned value to a new tensor using these three index. max(your_tensor). nn. shape=[b, l, c], and an index tesnor index. The selection over dimension 1 is specified by indices stored in a long tensor indices of shape [8]. 1Tensorの基本操作list, nda… Tensor. index_copy_ Copies the elements of tensor into the self tensor by selecting the indices in the order given in index. Dec 31, 2018 · Now I would like to make a selection of that tensor for each first dimension which results in a tensor of shape [8, 2]. abs((torch. For example, I have index tensor (size is [2, 4]) which is look like below: tensor([&hellip; Sep 19, 2018 · I want to fill a data tensor with a float given some index tensor. Tensor is the fundamental data structure of the machine or deep learning algorithms and to deal with them, we perform several operations, for which PyTorch library offers many functionalities. LongTensor([0, 1, 1, 3]) I want to sum all values in the data tensor where the values in the index tensor are equal. index_tensor. tensor ( [ [1,2,3,4], [5,6,7,8]]) idx = torch. May 12, 2018 · Here is a solution if you want to index a tensor in an arbitrary dimension and select a set of tensors from that dimension (an example is say we want to compute some average of the first 3 layers): Tensor. randn(4, 1040, 161) and I have another tensor called indices with values: tensor([[124, 583, 158, 529], [172, 631, 206, 577]], device='cuda:0') I Aug 27, 2023 · Hi, I’m trying to use index tensor to assign value to another tensor. 05 should be summed because the second and third value of idxs are equal. view (1,-1) c_2 = a [1] [idx [1]]. t() >> a[b. as_tensor function can also be helpful if your labels are stored in a list or numpy array:. Jul 10, 2023 · PyTorch tensor indexing provides a rich set of indexing operations that enable you to select and modify tensor elements using different indexing schemes, such as integer indexing, boolean indexing, and advanced indexing. Familiarize yourself with PyTorch concepts and modules. print((torch. Tutorials. import torch import random n_classes = 5 n_samples = 10 # Create list n_samples random labels (can also be numpy array) labels = [random. Jan 5, 2020 · 概要毎回調べてしまうpytorchのtensorの操作をまとめました公式のドキュメンテーション以上の内容はありません環境pytorch 1. as_tensor(labels) # Create one-hot encodings of labels one Run PyTorch locally or get started quickly with one of the supported cloud platforms. what is the best way to assign value to all the indices in the tensor? for exam May 12, 2020 · HI, torch uses same convention as numpy such for finding values or indices of particular tensor regarding specific condition. index_fill_ Fills the elements of the self tensor with value value by selecting the indices in the order given in index. PyTorch Recipes. Tensor. n<=l, max(n) <= len(l)-1 How to retrieve value tensor by index tensor? The following code seems to work perfectly but involve a for loop. I also have indices idx of the shape B x N x K where K < N. Tensor([ 0. gather and torch. squeeze(-1) squeezes the last dimension of the index tensor, making it a 1D tensor of indices. shape[:batch_dim], a[v] is the indices of the max element of tensor[v]. Speaking of the random tensor, did you notice the call to torch. More precisely, returns tensor `a` such that, for each index v of tensor. . 5, 0. For example, if dim == 0 , index[i] == j , and alpha=-1 , then the i th row of source is subtracted from the j th row of self . LongTensor([[1,1,1,1], [2,2,2,2], [0, 0, 0, 0]]). where and torch. I have a simple example for understanding. gather as it works across many dims, but torch I'm trying to slice a PyTorch tensor using a logical index on the columns. index_put_ (indices, values, accumulate = False) → Tensor ¶ Puts values from the tensor values into the tensor self using the indices specified in indices (which is a tuple of Tensors). Currently, I’m using this 使用 index_select 函数输出的张量维度和原始的输入张量维度相同。这也是为什么即使在对输入张量的其中一个维度的一个索引号进行索引 (此时可以使用基本索引和切片索引) 时也需要使用 PyTorch 中的高级索引方式才能与 index_select 函数等价的原因所在； Nov 9, 2018 · def batch_argmax(tensor, batch_dim=1): """ Assumes that dimensions of tensor up to batch_dim are "batch dimensions" and returns the indices of the max element of each "batch row". squeeze(-1)]: main_tensor[:, :] selects all rows. In case any integer between 0 and N-1 is missing, I want to return a -1. Adds all values from the tensor src into self at the indices specified in the index tensor in a similar fashion as scatter_(). nonzero. Apparently, T[:, L] gives a tensor of shape (x, x), where every element of L indexes every row. index_put_(indices, values) is equivalent to tensor[indices] = values . For each value in src , it is added to an index in self which is specified by its index in src for dimension != dim and by the corresponding value in index for dimension = dim . 2. e N points holding indexes on a target tensor of size [B,1,H,W]. Aug 30, 2018 · You can split b into 4 using chunk, and then use the chunked b to index the specific element you want: >> a = torch. index_reduce_ (dim, index, source, reduce, *, include_self = True) → Tensor ¶ Accumulate the elements of source into the self tensor by accumulating to the indices in the order given in index using the reduction given by the reduce argument. All index types such as None / / integer / boolean / slice / tensor are available in the C++ API, making translation from Python indexing code to C++ very simple. index_add_ (dim, index, source, *, alpha = 1) → Tensor ¶ Accumulate the elements of alpha times source into the self tensor by adding to the indices in the order given in index . as_tensor( [ [[1, 2, 3, 4, 5], [6, 7, 8, 9, 0], [11, 12, 13, 14, 15]], [[16, 17, 18, 19, 20], [21, 22, 23, 24, 25], [26, 27, 28, 29, 30]], ] ) index = [[0, 0, 1], [1, 2, 0]] # tensor([[ 6, 7, 8, 9, 0], # [11, 12, 13, 14, 15], Indexing a tensor in the PyTorch C++ API works very similar to the Python API. 0001). ignore value=1 positions which has no 2 a head. chunk(chunks=4, dim=0)] # here's the trick! Out[24]: tensor([[40, 80, 0]]) torch. # Create the main tensor. Suppose you have a tensor x of shape (3, 4), then you can use torch. Intro to PyTorch - YouTube Series Sep 20, 2020 · I am trying to understand the behavior of index_put in PyTorch, but the document is not clear to me. main_tensor = torch. Run PyTorch locally or get started quickly with one of the supported cloud platforms. 1000, -0. Oct 29, 2024 · main_tensor[:, index_tensor. Preferably without using a loop. jefu uphunmb rmidu ezvi ismrheu ludcc kvdk iymiu skul qxf