convert matrix in single column
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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
5 个评论
Sazzad Sayyed
2016-2-9
You can try matA=matA(:).This works.
muhammad komugabe
2017-10-18
great. thanx
Luke Handscomb
2018-4-6
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
2018-8-27
Transpose matrix first!
Image Analyst
2020-4-9
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.
采纳的回答
Andrei Bobrov
2012-4-18
yourvector = yourmatrix(:);
10 个评论
muhammad komugabe
2017-10-18
wow. it works fine
sayyam khurana
2017-11-20
NOT ALL HEROS WEAR CAPES.
Akash Singh
2018-12-12
I know it works fine, but how?
James Tursa
2018-12-12
Because (:) is the syntax in MATLAB for turning a variable into a column.
Mihai Gabriel Calitescu
2020-4-8
A man with this much power in his bare hands... im scared
Farid
2021-4-6
WOW
Pablo Moreno Galbis
2021-8-19
Drops the mic.
Paúl Aguilar
2021-9-16
Excelente, thanks sir.
rishika yadav
2022-7-14
HOW WE RESHAPE THE MATRIX WITH DIFFERENT ROW NO, AND SAME COLUMBS
Image Analyst
2022-7-14
编辑：Image Analyst
2022-7-14
m = reshape(1:18, [], 3) % Create 6 row by 3 column sample data
[oldHeight, columns] = size(m)
% Make the matrix taller by interpolating.
newHeight = 8;
[xq,yq] = meshgrid(1:columns, linspace(1, oldHeight, newHeight));
mTaller = interp2(m, xq, yq)
fprintf('The size of mTaller is %d rows by %d columns.\n\n', size(mTaller, 1), size(mTaller, 2))
% Make the matrix taller by interpolating.
newHeight = 3;
[xq,yq] = meshgrid(1:columns, linspace(1, oldHeight, newHeight));
mShorter = interp2(m, xq, yq)
fprintf('The size of mShorter is %d rows by %d columns.\n', size(mShorter, 1), size(mShorter, 2))
The first/top and last/bottom rows will have the same values, and more, or fewer, rows will be interpolated in between the top row and bottom row so that you have your new desired height.
更多回答（4 个）
Kyril Kaufmann
2020-4-26
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
Image Analyst
2012-4-18
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(:).)
7 个评论
yang liu
2018-3-31
hey, I want to know which is faster? command 'reshape()' or '(:)', are they two do the job based on the same underlying code? Thanks, I'm try to get my code running faster.
Image Analyst
2018-3-31
I would guess that (:) is faster, but they're going in opposite directions. Just use tic and toc a bunch of times to test it and see.
Akash Singh
2018-12-12
How is (:) working? I'm trying to understand the steps behind this method.
James Tursa
2018-12-12
编辑：James Tursa
2018-12-12
This has already been answered. The reason (:) turns a variable into a column is because MATLAB is programmed that way. That's what this particular syntax does. No other reason. There are no "steps" behind it. It is the equivalent of reshape(your_variable,numel(your_variable),1);
Wolfgang Klassen
2019-7-31
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
2019-10-25
I dont know but I have a 1056x2 matrix and it does not work, any clue?
James Tursa
2019-10-25
Please post a new Question with the details of your problem.
Rifat Hossain
2016-12-15
0 个投票
columnvector=matrix(:) this work fine
AMIR KHFAGI
2020-3-23
0 个投票
Hi, I have to convert one column vector to a matrix in matlab. How can I do this?
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