# Questions tagged [matrix]

In mathematics, a matrix (plural matrices) is a rectangular array of numbers, symbols, or expressions, arranged in rows and columns. The individual items in a matrix are called its elements or entries.

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### Trying to append elements to multi-dimensional array. Exception thrown when trying to run the application

int main(){int r;scanf("%d", &r);int **arr=(int *)malloc(r * r * sizeof(int));*(*(arr + r) + r);for (int i=1; i <=r; i++){for (int j=1; j <=r;...

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### Resampling and Rescale Numpy Matrix In Python [duplicate]

Is there any way in python to do matrix rescaling from M(4x4) to M(2x2) where the new matrix values are based on average of 2x2 old matrix values..? See picture below..The matrix is in numpy format.....

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### How to create a matrix with specified row and col names, from a dataframe containing the data and the names

If I have a dataframe like so:dataframe <- data.frame(Date=seq(as.Date("2018/01/01"), by="day", length.out=5),ID1=c(1, 2, 3, 4, 5),ID2=...

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### Getting unexpected results with MxN matrix

I have this basic template matrix class:template<class T, unsigned N>class Matrix {private:static const unsigned Stride=N;static const unsigned Size=Stride * Stride;T data[...

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### R: Remove items from a correlation matrix based on matching row and column name

Lets take a look at an example matrix and caclulate the correlations:some.data <- data.frame(A1.1=c(1,3,4,5,6),A1.2=c(4,5,6,2,3),A1.3=c(3,3,4,2,1),A2.1=c(3,4,5,2,4),A2.2=...

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### Exceedance rate for floods. matrixStats in R

I have been trying to estimate the exceedance rate of a matrix with values of water overtopping a dam.I basically used P=(RANK) /(n+1)where n, is the number of outcomes for the entire time of ...

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### GraphX - suitability for the multi-frontal solver

I represent a huge system of linear equations in a form of a tree in which all nodes are bound to small 7x7 matrices (3 of them really). To solve that system I need to perform operations on ...

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### Reading from a file and storing values as an array of arrays

I'm working on a program that would interpret some excel data to something more useful for me. But I really don't know how to move on on this.I have a csv file with matrix from excel, where are ...

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### multiple matrix row by row and column by column in python

I want to multiply 2 matrix with element of row by row and col by col as belowN=100; r=[ [0.5] , [0.01] , [0.04] , [0.01] ]; x1=np.random.randn(4,N);x2=np.tile(r,(1,N));x=np.multiply(np....

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### How can I conclude that two Signals are co related using Dynamic Time wrapping?

So I have just started looking into DTW for applying it on one of the problems for my research. I am trying to take set of 2 D points (2D matrix) and using PCA to change its orientation. I want to ...

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### How to loop through every possible diagonal from 2D MultiArray using Numpy Python package?

I am trying to use python numpy package to find out every possible diagonal combination (continuous) from a 7*7 MatrixBut I find out it only check the first diagonal and stopPlease help me in this ...

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### Generate a Weight Transfer Matrix (or a Transition Matrix) for a Direct Graph (as a pandas dataframe)

I have a pandas dataframe:I want to generate a weight transfer matrix, M(10000*10000) for this graph without using a loop in python (as loops are taking a lot of time) for PageRank computation. For ...

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### converting an excel program to a python program for pH meter tables

I study chemistry and we're using pH meters. Our professor gave us a Microsoft Excel spreadsheet which, given a table with ml vs. pH values, plots:the sigmoid graph,the first derivative graph and...

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### Can't multiply sequence by 'float' on Inverse Matrix Function (Python 3.6)

I'm trying to make a function that inverses entered 4 x 4 matrix I am not allowed to use module or array, only 'list' and 'nested list comprehension'are allowed to useThis is all of my script ...

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### C# - 2d matrix - is guess left/right/up/down of point

Using a 2d array of buttons implemented and placed on a form.Button[,] tmpButton=new Button[x, y];private void DrawGrid(){int ButtonWidth=48;int ButtonHeight=48;int start_x ...