# convert matrix in single column

4.686 views (last 30 days)
Gaetano Sciacovelli on 18 Apr 2012
Answered: Kyril Kaufmann on 26 Apr 2020
Hi, I have to convert a matrix in one column vector composed of all the columns of the original matrix. How can I do this? Thanks

Luke Handscomb on 6 Apr 2018
This takes column1 and then appends column2 to the bottom of 1 and 3 to 2 and so on. What if I wanted to instead arrange it as row1+row2+row3....? Cheers
Ndilokelwa Luis on 27 Aug 2018
Transpose matrix first!
Image Analyst on 9 Apr 2020
You said "I have to convert a matrix in one column vector composed of all the columns of the original matrix." I thought you meant you had a column vector and had to convert it to a matrix having the same number of columns as the original matrix from where the column vector came. In other words, I thought you meant "I have to convert a matrix of one column vector INTO ONE composed of all the columns of the original matrix."
Seeing the answer you accepted, it appears that you actually meant "I have to convert a matrix INTO a one column vector that is composed of all the columns of the original matrix." Leaving out seemingly minor words completely changes the interpretation of the question, as does their placement in the sentence.

Andrei Bobrov on 18 Apr 2012
yourvector = yourmatrix(:);

Akash Singh on 12 Dec 2018
I know it works fine, but how?
James Tursa on 12 Dec 2018
Because (:) is the syntax in MATLAB for turning a variable into a column.
Mihai Gabriel Calitescu on 8 Apr 2020
A man with this much power in his bare hands... im scared

Image Analyst on 18 Apr 2012
If your column vector was "composed of all the columns of the original matrix", then use the reshape() command to turn it from a column vector back into the original 2D matrix.
matrix2D = reshape(columnVector, [rows columns]);
(The converse, how to get the column vector in the first place (what you may have done to get your vector) is accomplished like this columnVector = fullMatrix(:).)

Wolfgang Klassen on 31 Jul 2019
Matlab has multiple kinds of indexing, and which one gets used is often a function of how many indices you use. A(2,3) accesses the element in the second row, third column. A(6) accesses the sixth element in the matrix, starting numbering in the first column and going down the columns until you get to the end. Just like you might say A(1,:) accesses all the columns in the first row, A(:) accesses all the elements in that ordering scheme, which happens to be all the elements in the matrix, in a particular order. If you wanted a different order, you'd have to use reshape, or maybe transpose it first.
Surya Kanthi on 25 Oct 2019
I dont know but I have a 1056x2 matrix and it does not work, any clue?
James Tursa on 25 Oct 2019

Kyril Kaufmann on 26 Apr 2020
For a more algorithmic solution:
% From matrix to vector
N = 10;
mat1 = rand(N);
vec1 = zeros(N*N,1);
for i=1:N
for j=1:N
vec1((i-1)*N + j) = mat1(i,j);
end
end
% From vector to matrix
N = 10;
vec2 = rand(N*N,1);
mat2 = zeros(N);
for i=1:N
for j=1:N
mat2(i,j) = vec2((i-1)*N + j);
end
end

Rifat Hossain on 15 Dec 2016
columnvector=matrix(:) this work fine

AMIR KHFAGI on 23 Mar 2020
Hi, I have to convert one column vector to a matrix in matlab. How can I do this?

#### 1 Comment

Shuyun Yuan on 7 Apr 2020
reshape function