Questions tagged [elementwise-operations]
204 questions
2
votes
1 answer
Torch Element-wise Logical Operation and/or
I am trying to perform logical element-wise opertaions on tensors, but it seems "and" keyword performs logical or, while "or" keyword performs logical and :
a = torch.zeros(3)
a[1] = 1 -- a will be [1,0,0]
b =…
kerrigan
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- 9
2
votes
1 answer
Sparse matrix multiplication in MATLAB with spfun
I have a dense column matrix y of size (m,1) and a sparse matrix x of size (m,n).
I want to do element-wise multiplication using y and every column of x.
The resultant sparse matrix is still of size (m,n).
Sparse matrix x, when loaded into memory,…
user3630879
2
votes
1 answer
Efficient 3D element-wise operations in MATLAB
Say i have two martrices:
A=50;
B=50;
C=1000;
X = rand(A,B);
Y = rand(A,B,C);
I want to subtract X from each slice C of Y. This is a fairly common problem and i have found three alternative solutions:
% Approach 1: for-loop
tic
Z1 =…
Nolan Conaway
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2
votes
3 answers
Mathematica: adding a list of lists elementwise
I have a list of lists of numbers. I add them into one list by adding all of the first elements together, all of the second elements together, etc. For example, if my list were { {1,2,3}, {1,2,3}, {1,2,3,4} } I would want to end up with {3,6,9,4}.…
Kate
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- 2
2
votes
1 answer
Compare OpenCV Mat with scalar elementwise
I have a cv::Mat A, which has CV_32F. However it holds integer values like 1,2....100. I want to form a mask of same size as A.
But the mask must contain zeros if A(x,y) not equal to 5 (say).
The mask must contain ones if A(x,y) equal to 5 (say).
I…
mkuse
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2
votes
2 answers
Calculating the powers of a vector elementwise
I have a vector [x, y, ...] in Octave and I would like to take the pth powers of the elements to get the new vector [x^p, y^p, ...]. Anybody has an idea how to do this?
zoli
- 145
- 3
1
vote
1 answer
How do I collapse (element-wise for maximum, minimum, or mean) a multi-dimensional numpy array for a subset of indices along a specific axis?
I currently have a numpy array of the shape (71, 136, 136, 130); the exact dimensions vary. This is volume data (e.g., temperature) in the form [Time, Z, Y, X]. I am allowing the user to specify the time range to collapse the Z, Y, X volume…
wein3967
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1
vote
0 answers
Elementwise Comparison of Numpy Arrays
I would like to ask a question for the table below for the comparison of np arrays:
Ticket Travel Time Price
A 10 1700
B 9 2000
C 8 1800
D 7.5 2300
E 6 …
Dinc Kirikci
- 47
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1
vote
1 answer
Writing {value} +- {uncertainty} in matrix. How does that work with sympy?
I have two 6x6 matrices. Here I'll just show the first two rows and columns:
import sympy as sp
values = sp.Matrix([[-0.403900000000000, 0.158730000000000], [-1.52350000000000, -1.87937000000000]])
uncertainties = sp.Matrix([[0.000600000000000000,…
Tasha
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1
vote
1 answer
How do I do an elementwise sum of the current element and next three row elements (in column 0) using array operations not a for loop?
I am trying to do an operation relative to the location of the element
during an elementwise numpy operation. I cannot figure out how access
the current location in order to sum it with the next three elements.
I have included a sample array as…
registerrug
- 33
- 4
1
vote
2 answers
Python namedtuples elementwise addition
Is there a more pythonic way to implement elementwise addition for named tuples?
Using this class that inherits from a namedtuple generated class named "Point I can do elementwise addition for this specific named tuple.
class…
Isaacnfairplay
- 217
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1
vote
1 answer
Problem with element-wise operations in numpy
This is my first Question here, let me know if I could've done anything better.
I'm trying to do a element-wise operation between two arrays, but the broadcasting wont work like I want it to.
I have an array of shape (N,4).
square_list =…
Klaus
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1
vote
3 answers
element-wise averages of two (or more) nested lists of matrices
I have two lists A_1 and A_2, each contains two matrices.
A_1 <- list(a=matrix(1:8, 2), b=matrix(2:9, 2))
A_2 <- list(a=matrix(10:17, 2), b=matrix(5:12, 2))
I'd like to calculate element-wise averages of these two lists which results a list…
hnguyen
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1
vote
1 answer
per-element vector multiplication with gurobipy
The last line of this code fails:
A = np.random.rand(d, d)*5.0
b = np.random.rand(d)*10.0
m = gp.Model()
x = m.addMVar(d, name='x')
y = m.addMVar(d, name='y', vtype=gp.GRB.BINARY)
m.addConstr(A@x <= b)
m.addConstr(A@x >= y*b) // error occurs here on…
Brannon
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1
vote
1 answer
Calculating the differences between series of correlation matrixes (as DataFrames, pandas) in python
From a series of DataFrames that contain daily log returns of a large number of stocks, eg:
data_list = [data_2015, data_2016, data_2017, data_2018, data_2019, data_2020]
The task at hand is to compute the change in the correlations between each…
citizen_1571989
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