numpy-broadcasting

What are the rules for comparing numpy arrays using ==?

我只是一个虾纸丫 提交于 2019-12-01 16:30:04
问题 For example, trying to make sense of these results: >>> x array([0, 1, 2, 3, 4, 5, 6, 7, 8, 9]) >>> (x == np.array([[1],[2]])).astype(np.float32) array([[ 0., 1., 0., 0., 0., 0., 0., 0., 0., 0.], [ 0., 0., 1., 0., 0., 0., 0., 0., 0., 0.]], dtype=float32) >>> (x == np.array([1,2])) False >>> (x == np.array([[1]])).astype(np.float32) array([[ 0., 1., 0., 0., 0., 0., 0., 0., 0., 0.]], dtype=float32) >>> (x == np.array([1])).astype(np.float32) array([ 0., 1., 0., 0., 0., 0., 0., 0., 0., 0.],

Explanation on Numpy Broadcasting Answer

丶灬走出姿态 提交于 2019-12-01 08:12:24
I recently posted a question here which was answered exactly as I asked. However, I think I overestimated my ability to manipulate the answer further. I read the broadcasting doc, and followed a few links that led me way back to 2002 about numpy broadcasting. I've used the second method of array creation using broadcasting : N = 10 out = np.zeros((N**3,4),dtype=int) out[:,:3] = (np.arange(N**3)[:,None]/[N**2,N,1])%N which outputs: [[0,0,0,0] [0,0,1,0] ... [0,1,0,0] [0,1,1,0] ... [9,9,8,0] [9,9,9,0]] but I do not understand via the docs how to manipulate that. I would ideally like to be able to

TensorFlow broadcasting

拜拜、爱过 提交于 2019-12-01 07:32:45
问题 Broadcasting is the process of making arrays with different shapes have compatible shapes for arithmetic operations. In numpy, we can broadcast arrays. Does TensorFlow graph support broadcasting similar to the numpy one? 回答1: yes it is supported. Open a terminal and try this: import tensorflow as tf #define tensors a=tf.constant([[10,20],[30,40]]) #Dimension 2X2 b=tf.constant([5]) c=tf.constant([2,2]) d=tf.constant([[3],[3]]) sess=tf.Session() #start a session #Run tensors to generate arrays

Explanation on Numpy Broadcasting Answer

ぐ巨炮叔叔 提交于 2019-12-01 07:12:31
问题 I recently posted a question here which was answered exactly as I asked. However, I think I overestimated my ability to manipulate the answer further. I read the broadcasting doc, and followed a few links that led me way back to 2002 about numpy broadcasting. I've used the second method of array creation using broadcasting: N = 10 out = np.zeros((N**3,4),dtype=int) out[:,:3] = (np.arange(N**3)[:,None]/[N**2,N,1])%N which outputs: [[0,0,0,0] [0,0,1,0] ... [0,1,0,0] [0,1,1,0] ... [9,9,8,0] [9,9

How does pytorch broadcasting work?

痴心易碎 提交于 2019-12-01 06:39:28
torch.add(torch.ones(4,1), torch.randn(4)) produces a Tensor with size: torch.Size([4,4]) . Can someone provide a logic behind this? PyTorch broadcasting is based on numpy broadcasting semantics which can be understood by reading numpy broadcasting rules or PyTorch broadcasting guide . Expounding the concept with an example would be intuitive to understand it better. So, please see the example below: In [27]: t_rand Out[27]: tensor([ 0.23451, 0.34562, 0.45673]) In [28]: t_ones Out[28]: tensor([[ 1.], [ 1.], [ 1.], [ 1.]]) Now for torch.add(t_rand, t_ones) , visualize it like: # shape of (3,)

How does pytorch broadcasting work?

半腔热情 提交于 2019-12-01 05:32:39
问题 torch.add(torch.ones(4,1), torch.randn(4)) produces a Tensor with size: torch.Size([4,4]) . Can someone provide a logic behind this? 回答1: PyTorch broadcasting is based on numpy broadcasting semantics which can be understood by reading numpy broadcasting rules or PyTorch broadcasting guide . Expounding the concept with an example would be intuitive to understand it better. So, please see the example below: In [27]: t_rand Out[27]: tensor([ 0.23451, 0.34562, 0.45673]) In [28]: t_ones Out[28]:

NumPy indexing: broadcasting with Boolean arrays

99封情书 提交于 2019-12-01 01:13:33
Related to this question , I came across an indexing behaviour via Boolean arrays and broadcasting I do not understand. We know it's possible to index a NumPy array in 2 dimensions using integer indices and broadcasting. This is specified in the docs : a = np.array([[ 0, 1, 2, 3], [ 4, 5, 6, 7], [ 8, 9, 10, 11]]) b1 = np.array([False, True, True]) b2 = np.array([True, False, True, False]) c1 = np.where(b1)[0] # i.e. [1, 2] c2 = np.where(b2)[0] # i.e. [0, 2] a[c1[:, np.newaxis], c2] # or a[c1[:, None], c2] array([[ 4, 6], [ 8, 10]]) However, the same does not work for Boolean arrays. a[b1[:,

Forcing multiplication to use __rmul__() instead of Numpy array __mul__() or bypassing the broadcasting

北慕城南 提交于 2019-11-30 22:22:53
This question is close to what is asked in Overriding other __rmul__ with your class's __mul__ but I am under the impression that this is a more general problem then only numerical data. Also that is not answered and I really don't want to use the matrix multiplication @ for this operation. Hence, the question. I do have an object which accepts multiplication with scalars and numerical arrays. As usual, the left multiplication works fine since it is the myobj() methods are used but in the right multiplication, NumPy uses broadcasting rules and gives elementwise results with dtype=object . This

NumPy indexing: broadcasting with Boolean arrays

China☆狼群 提交于 2019-11-30 20:02:24
问题 Related to this question, I came across an indexing behaviour via Boolean arrays and broadcasting I do not understand. We know it's possible to index a NumPy array in 2 dimensions using integer indices and broadcasting. This is specified in the docs: a = np.array([[ 0, 1, 2, 3], [ 4, 5, 6, 7], [ 8, 9, 10, 11]]) b1 = np.array([False, True, True]) b2 = np.array([True, False, True, False]) c1 = np.where(b1)[0] # i.e. [1, 2] c2 = np.where(b2)[0] # i.e. [0, 2] a[c1[:, np.newaxis], c2] # or a[c1[:,

Forcing multiplication to use __rmul__() instead of Numpy array __mul__() or bypassing the broadcasting

谁说我不能喝 提交于 2019-11-30 17:20:17
问题 This question is close to what is asked in Overriding other __rmul__ with your class's __mul__ but I am under the impression that this is a more general problem then only numerical data. Also that is not answered and I really don't want to use the matrix multiplication @ for this operation. Hence, the question. I do have an object which accepts multiplication with scalars and numerical arrays. As usual, the left multiplication works fine since it is the myobj() methods are used but in the