For a matrix with an unknown number of rows, how to find the number of rows n and transform it into n matrices.

[Stephen23]

"... how to find the number of rows n and transform it into n matrices."

https://www.mathworks.com/help/matlab/ref/mat2cell.html

https://www.mathworks.com/help/matlab/ref/num2cell.html

[Wesley]

I‘d like to automatically divide the matrices and express these matrices as point coordinates. But I still can't achieve it.

[Jan]

What does "express as point coordinates" mean? Please post a specific example.

[Wesley]

I think it should be a loop statement to achieve such a function. The coordinates of a point can be written as A1=(X1,Y1), A2=(X2,Y2),..., An=(Xn,Yn). I am a beginner and cannot write programs proficiently. So I would like to ask you how to implement it by program.

[Wesley]

As shown in the figure, I’d like to express the data in the table as points. For example, A1=(237,165), A2=(238,165),..., An=(222,170).

[Stephen23]

"I think it should be a loop statement to achieve such a function."

https://en.wikipedia.org/wiki/XY_problem

https://xyproblem.info

Tells us what you are actually trying to do.

[Wesley]

In so much data, find the largest y1, y2 and the coordinates of their respective points.

[Wesley]

B=A, expand into A=[A1 A2 A3 A4].

Answer 1

[Ameer Hamza]

You can find the number of rows in a matrix using size()

data1; 
n = size(data,1)

or height() [only in R2020b and later]

data1; 
n = height(data)

The second part of your question about transforming it into a matrix is not clear.

Answer 2

[Ameer Hamza]

I guess you are trying to do something like this

rows = data1(:,2);
cols = data1(:,1);

M = zeros(max(rows), max(cols));
idx = sub2ind(size(M), rows, cols);
M(idx) = 1;

Result

>> imshow(M)

[Wesley]

I have solved this problem. My goal is to find the largest y1, y2 and the coordinates of their respective points.

[Ameer Hamza]

What do you mean by y1 and y2?

[Wesley]

The two largest numbers in a column.

[Ameer Hamza]

You can use maxk() to get two largest values. For example

maxk(data1, 2)

gives 2 highest values in both columns.