count rows in matrix ?

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Rakesh Praveen
Rakesh Praveen 2011-11-7
编辑： MathWorks Support Team 2020-11-4
hey, i want to know is there a way to get how many rows are there in a given matrix. like for example when we say 'length(A)' it can give number of columns in a matrix(A), likewise can we know about number of rows ?
thank you.
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Image Analyst
Image Analyst 2016-10-16
height() doesn't work on matrices -- it only works on tables.
morteza HEIDARI
morteza HEIDARI 2017-8-15
编辑：morteza HEIDARI 2017-8-15
If for example your matrix is A, you can use : size(A,1) for number of rows. size(A,2) for number of columns. Also there are some other ways like : length ( A(:,1) ) for number of rows.

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Oleg Komarov
Oleg Komarov 2011-11-7
编辑：MathWorks Support Team 2020-11-4
size(A,1)
The following documentation provides more information on 'size' function:
https://www.mathworks.com/help/matlab/ref/size.html
Starting in R2020b, you can also use "height" and "width" function to count rows and columns of a matrix respectively.
For example:
A=rand(3,2); %Defining a matrix;
count_rows=height(A); %Computes number of rows in A
count_columns=width(A); %Computes number of columns in A
For more information on "height" and "width" functions, please refer to the following documentation:
https://www.mathworks.com/help/releases/R2020b/matlab/ref/height.html
https://www.mathworks.com/help/releases/R2020b/matlab/ref/width.html
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Hoang-Linh To
Hoang-Linh To 2014-5-19
Thank you so much, that's also what I want :)
Pooja
Pooja 2014-9-22
It workd for me also. Thankyou Oleg Komarov

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更多回答（5 个）

Ashutosh Kumar
Ashutosh Kumar 2016-7-22
length(A) gives you maximum out of the matrix made by calling the size,so it doesn't give you column(A) and for calling column(A) you need size(A,2) and for row you need size(A,1)...like suppose you have a 5*4 matrix then length(A) will give you 5 number of rows not 4...Hope that will help others I myself used length(A) and ended up making a wrong code and took me 2 hours to do it right
Image Analyst
Image Analyst 2011-11-7
For a 2D matrix:
[rows columns] = size(array2D);
or, in general,
sizeOfMatrix = size(yourMatrix);
Thulitha Theekshana
I think the best way is to use size(x,y) function.
ex: if you want to get the height, size(matrix_name, 1). Here the second variable denotes the dimensioin you need to measure. From one it means the number of rows or the first dimension. From 2 it means the number of columns or the length. So I think you get the idea,
Gaganjyoti Baishya
Gaganjyoti Baishya 2020-6-20
It's simple. You can see the size of the first column, that will be the rows in matrix.
rows = size(myMatrix, 1); % first row length
Anurag Pratap Singh
Hi Rakesh
For counting the number of rows in a matrix you can use the size funtction and pass your matrix in it
[NumRows NumCols]=size(your_matrix);
The first output is the Number of rows .
Thank you

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