Adding a column every nth column without replacing existing one
9 Ansichten (letzte 30 Tage)
Ältere Kommentare anzeigen
Enthusiasten
am 11 Dez. 2019
Kommentiert: Adam Danz
am 12 Dez. 2019
Hey all,
I am looking for a solution to the problem I mentioned in the title.
FOr example, I have matrix A
A = [1 2 3 4; 5 6 7 8; 9 10 11 12];
I now want to add every 2nd (and later 3th) column a new column containing zeros.
The result should be like this:
result = [1 0 2 0 3 0 4 0; 5 0 6 0 7 0 8 0; 9 0 10 0 11 0 12 0];
I know how to create a new column containg only zeros
B = zeros(number_of_rows,1);
Previously, I used
C = [A(:,1:2) B A(:,2+1:end)];
But this only works for a specific column and not every nth column.
Thanks for your answers in advance!
0 Kommentare
Akzeptierte Antwort
Adam Danz
am 11 Dez. 2019
Bearbeitet: Adam Danz
am 11 Dez. 2019
The variable n indicates every n-columns that should be 0s. It must be an integer greater than 1.
See inline comments for details.
% INPUTS
A = [1 2 3 4; 5 6 7 8; 9 10 11 12];
n = 2; % for n=2, every 2nd col will be 0s
% Determine the number of columns of resultant matrix
nCol = floor(size(A,2)/(n-1)*n);
% matrix of all 0s
result = zeros(size(A,1),nCol);
% Determine column indices of non-zeros
colIdx = 1:nCol;
colIdx(n:n:end) = [];
% Insert values from A into result matrix
result(:,colIdx) = A
3 Kommentare
Weitere Antworten (2)
Max Murphy
am 11 Dez. 2019
Test Data
A = [1 2 3 4; 5 6 7 8; 9 10 11 12];
Function
function A = addDataNthColumn(A,B,n)
% ADDDATANTHCOLUMN Add data in column vector or matrix B to every nth
% column of A
if nargin < 3
n = 3;
end
if size(A,1) ~= size(B,1)
error('A and B must have same number of rows');
end
if size(A,2) >= n
% Use recursion to iterate on A
A = [A(:,1:(n-1)), B, addDataNthColumn(A(:,n:end),B,n)];
else
A = [A, B]; % Last "set" just concatenate them
end
end
Usage
>> test = addDataNthColumn(A,zeros(3,2),2)
test =
1 0 0 2 0 0 3 0 0 4 0 0
5 0 0 6 0 0 7 0 0 8 0 0
9 0 0 10 0 0 11 0 0 12 0 0
5 Kommentare
Adam Danz
am 11 Dez. 2019
Well there must have been good thresholding on your instrumentation, then. It's such a good feeling to work with an isolatable single neuron but mult-iunit activity is also fun. Now you have me all nostalgic.
Chuguang Pan
am 12 Dez. 2019
It is every 2th column. Now I put it in Answer this question
rowA=size(A,1);
colA=size(A,2);
B=zeros(rowA,colA*2);
B(:,1:2:2*colA)=A;
Siehe auch
Kategorien
Mehr zu Get Started with MATLAB finden Sie in Help Center und File Exchange
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!