matrix Questions
4
Solved
I'm implementing Strassen's Matrix Multiplication using python. In divide step, we divide a larger matrix into smaller sub-matrices. Is there a built-in numpy function to split a matrix?
3
I am trying to create a randomized matrix in R. It needs to be a presence/absence matrix, such that all values in the matrix are either 0 or 1.
But I also need to specify row and column totals, for...
Parapodium asked 17/4, 2023 at 23:2
2
Solved
all, I have a correlation matrix of 21 industry sectors. Now I want to split these 21 sectors into 4 or 5 groups, with sectors of similar behaviors grouped together.
Can experts shed me some light...
Schmit asked 12/10, 2018 at 21:53
6
I have several vectors of unequal length and I would like to cbind them. I've put the vectors into a list and I have tried to combine the using do.call(cbind, ...):
nm <- list(1:8, 3:8, 1:5)
do...
2
Solved
I am trying to make a fixed-size matrix class. The intent is to make it inherit or utilize a std::array of std::array:
template <size_t Rows, size_t Columns, class T=double>
struct Matrix : p...
3
Solved
I have a dataset, X, with n rows and d columns.
I want to take the dot product with each row to the transpose of itself. In R code this would be x %*% t(x), and this gives a d by d matrix.
I then t...
Counterweigh asked 10/4, 2023 at 12:28
6
Solved
I have a numeric matrix with 25 columns and 23 rows, and a vector of length 25. How can I multiply each row of the matrix by the vector without using a for loop?
The result should be a 25x23 matri...
Colcothar asked 4/9, 2010 at 18:51
5
Given the following matrix lets assume I want to find the maximum value in column two:
mat <- matrix(c(1:3,7:9,4:6), byrow = T, nc = 3)
mat
[,1] [,2] [,3]
[1,] 1 2 3
[2,] 7 8 9
[3,] 4 5 6
I ...
9
Solved
It is wanted of me to implement the following function:
void calc ( double* a, double* b, int r, int c, double (*f) (double) )
Parameters a, r, c and f are input and b is output. “a” and “b”...
15
Solved
I'm trying to come up with a solution that takes in a matrix like this:
[[1,2,3,4],
[5,6,7,8],
[9,10,11,12],
[13,14,15,16]]
and returns an array traversing the array as a spiral, so in this e...
Glycerol asked 18/6, 2015 at 4:19
4
Solved
I have a nx1 matrix I want to convert this to a nxn diagonal matrix in R
3
Solved
Suppose I have a matrix foo as follows:
foo <- cbind(c(1,2,3), c(15,16,17))
> foo
[,1] [,2]
[1,] 1 15
[2,] 2 16
[3,] 3 17
I'd like to turn it into a list that looks like
[[1]]
[1] 1 15
...
6
Solved
Is there a quick way to "unpivot" an Excel matrix/pivot-table (in Excel or elsewhere), without writing macros or other code ?
Again, I can write code (C# or VBA or whatever) that does that myselfs...
1
Solved
I'd like to write a %*% method for a base matrix subclass. My subclass is an S3 class and the documentation of help("%*%") says that %*% is a S4 generic and that S4 methods need to be wri...
25
Solved
I've got an array of arrays, something like:
[
[1,2,3],
[1,2,3],
[1,2,3],
]
I would like to transpose it to get the following array:
[
[1,1,1],
[2,2,2],
[3,3,3],
]
It's not difficult to...
Intra asked 2/7, 2013 at 14:43
1
I want to implement non-negative matrix factorization using PyTorch. Here is my initial implement:
def nmf(X, k, lr, epochs):
# X: input matrix of size (m, n)
# k: number of latent factors
# lr:...
Albion asked 15/3, 2023 at 9:14
5
Solved
I have an existing covariance matrix and I would like to convert it to become block diagonal based on which groups the individual columns belong to (e.g. 1st 2 rows/columns are group 1, next are gr...
2
Solved
Is there a function to get an index (row number and column number) for a matrix?
Suppose that I have a simple matrix:
a <- matrix(1:50, nrow=5)
Is there an easy way to get back something li...
2
Solved
I am currently trying to speed up my large sparse (scipy) matrix multiplications. I have successfully linked my numpy installation with OpenBLAS and henceforth, also scipy. I have run these tests w...
Intermittent asked 2/8, 2014 at 19:32
4
Solved
In python, suppose I have a square numpy matrix X, of size n x n and I have a numpy vector a of size n.
Very simply, I want to perform a broadcasting subtraction of X - a, but I want to be able t...
Brahmanism asked 7/9, 2016 at 4:41
2
Solved
The writematrix command can write matrices to text files. For example, for a matrix like the following
A = [1, 2, 3, 4];
It can be written to file a.txt using the writematrix command
A = [1, 2, 3,...
8
Solved
I'm trying to ask the user to enter the number of columns and rows they want in a matrix, and then enter the values in the matrix... I'm going to let them insert numbers one row at a time.
How can...
4
Solved
I have a matrix that contains economic information on industries for several countries. I want to do a series of calculations that depend on the positioning of the element in the matrix and the cor...
6
Solved
3
Solved
What is the quickest way to convert the non-diagonal elements of a square symmetrical numpy ndarray to 0?
Fenner asked 5/12, 2017 at 7:14
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