Sequence of submatrix based on the position of a rectangle

I found the method to derive the submatrix (based on the position of the rectangle that I select through imagesc-> Insert-> rectangle) from the original matrix. Follow the link:

http://www.mathworks.it/matlabcentral/answers/13951-how-to-create-image-matrix-via

But now I have a sequence of matrices, not just one, and I should find the respective submatrices selecting only that rectangle. How can i do?

[Jan]

Could you explain an example of the available inputs and the wanted output?

[Walter Roberson]

Duplicate is at http://www.mathworks.com/matlabcentral/answers/17973-block-to-make-a-loop-to-find-a-sequence-of-submatrix

[Vincenzo]

I deleted it!

That's the post. ;)

Answer 1

[Vincenzo]

I load all the matrices, then on the first matrix I do imagesc-> Insert-> rectangle ... after I click with right mouse button shows M code, which gives me the position, respectively [left bottom width height]. Due to the location, I have the coordinates to calculate the single submatrix but I would like to calculate the other. Submatrix is Usally Submatrix= NameOriginalMatrix =(row1: row2, column1: column2) But if i have 10 matrices with the same number of rows and columns (matrix1, matrix2,.... Matrix10), in output I would like to automatically calculate the other like this:

submatrix1= matrix1 (row1: row2, column1: column2);

submatrix2 =matrix2 (row1: row2, column1: column2);

. . . submatrix10 =matrix10 (row1: row2, column1: column2);

All this only with the position of a rectangle

[Walter Roberson]

http://matlab.wikia.com/wiki/FAQ#How_can_I_create_variables_A1.2C_A2.2C....2CA10_in_a_loop.3F

[Image Analyst]

I don't see a question. You've stated what you need, and given a solution to it in only 10 lines, so as I see it, you're all set.

Answer 2

[Vincenzo]

No, i'm not all set.

What i think i should do:

1)Load all the matrices

2)Write in a .mat or another kind of file the following things:

% [x1 y1 width hight] coordinates of part of image i selected

x1=...; y1=...; x2=x1+width; y2=y1+hight;

[rows columns numberOfColorChannels]=size(NameOfAMatrix);

row1=int32(x1*columns);

row2=int32(x2*columns);

column1=int32(y1*rows);

column2=int32(y2*rows);

N=500 ; % number of matrices

for i=1:N

sub(i)=Matrix(i)(row1:row2,column1:column2)[1]*

end %end of file

3)just call the file[2*]

[1*]The real problem is to implement automatically the matrices...the name are Seq1,...,Seq500, so if i do sub(i)=Seq(i)(row1:row2,column1:column2) i call all the matrices or not?

[2*]What kind of file?

The 3 steps are right or not?

Answer 3

[Image Analyst]

In (2), you're getting rows and columns confused. x is columns and y is rows. So this

    row1=int32(x1*columns);

is meaningless. I have no idea what you're asking in (3). The code you tried to write in 2 should be put into an "m-file" with the text editor. Then you'd run that. .mat files are usually for storing data (variables) and never used for storing source code. Seems like you need to go through the Getting Started guide.

Answer 4

[Vincenzo]

Yes..i want to write column1=int32(x1*columns) and row1=int32(y1*rows) ;)

The syntax for the .m file i see it's not all right

What i write:

N=10;

x1=0.4196; y1=0.6238; width=0.1446; hight=0.1286; x2=x1+width; y2=y1+hight;

[rows columns numberOfColorChannels]=size(Seq9);

column1=int32(x1*columns);

column2=int32(x2*columns);

row1=int32(y1*rows);

row2=int32(y2*rows);

for i=1:N

sub{i}=Seq{i}(row1:row2 ,column1:column2); %Here is the error

i=i+1;

end

but when i call >>name_of_file it says to me: "??? Undefined variable "Seq" or class "Seq". "

I write Seq only because i want to automatically implements Seq1,...,Seq10(name of matrices)..what's wrong?

Please I need your help!!!

Answer 5

[Image Analyst]

I don't think you can do this Seq{i}(row1:row2 ,column1:column2); first of all, you'd need to have Seq previously defined and created, which I don't think you have, based on the error message. Then, assuming you did stuff an array into Seq{i} I'd extract it like this

m = Seq{i}; sub{i} = m(row1:row2, column1:column2);

Finally, incrementing i (i=i+1) inside a for loop does nothing - it ignores it and follows the iteration set up on the "for" line. Changing the iterator ("i") inside the loop as no effect on the number of iterations that take place, as discussed in this forum before.

Answer 6

[Vincenzo]

I add:

 [rows ....numberOf...]=size (Seq); %[1*]
.
.
 for i=1:N

m=Seq{i};

sub{i}=m(row1:row2, column1:column2); %[2*]

end

i=i+1;

% these are the messages:

%[1*] Variable 'Seq' is used, but apparently not set

%[2*] sub might be growing inside a loop.Consider preallocating for speed

I declared in the workspace Seq, but when you say "... Then, assuming you did stuff an array into Seq{i}.." what i have to do exactly? I don't understand

Answer 7

[Vincenzo]

I have the following matrices Seq001...Seq009,Seq010..Seq099,Seq100...Seq999

what i did:

% namefile.m

N=999;

x1=0.4196;

y1=0.6238;

width=0.1446;

hight=0.1286;

x2=x1+width;

y2=y1+hight;

[rows columns numberOfColorChannels]=size(Seq009);

column1=int32(x1*columns);

column2=int32(x2*columns);

row1=int32(y1*rows);

row2=int32(y2*rows);

name='Seq';

sub='sub';

subunit=sub+'0'+'0';

subdecina=sub+'0';

for i=1:N

 if (i<=9)

 unit=name+'0'+'0'+'i'; % from Seq001 to Seq009

 subunit1=subunit+'i'; [*]  % from sub001  to sub009

 subunit1=unit(row1:row2 ,column1:column2); % line 38

 end

 if (i>=10 && i<=99)

     decina=name+'0'+'i'; % from Seq010 to Seq099

     subdecina1=subdecina+'i'; [**] % from sub010  to sub099

    subdecina1=decina(row1:row2 ,column1:column2);

 end

 if(i>=100 && i<=999)

     centinaia=nome+'i'; % from Seq100 to Seq999 

     subcentinaia=sub+'i'; [***] % from sub100  to sub999

     subcentinaia=centinaia(row1:row2 ,column1:column2);

 end

end

i=i+1;

...now if i do>> namefile it says:

" ??? Index exceeds matrix dimensions. at line 38"

and in .m file i have 3 warnings in the lines that i marked with [*],[**],[***] having the same advice: "The value assigned here to variable 'subunit1'/'subdecina1'/'subcentinaia' might be never used"

Why?? It looks to me right but it's not.

Answer 8

[Vincenzo]

Is there a string concatenation method in wich i can recall the matrices?...Because i need a dynamic vector containing all the matrices(bu i don't want write all statically)..Maybe a method which i can concatenate:

 name='Seq';
 number1='0';
number2='0'

N=5;

for i=1:N

example=name+number1+number2+i

%here i would that appear Seq001,...,Seq005 that are linked with the matrices Seq001,...,Seq005 but indeed it appears example='Seq00'..just a string and not the matrix...how can i do?

Please someone can help me?? I have no idea!!!

end

i=i+1;

[Vincenzo]

Or call always in a .m file all the matrices that are in a folder: C:\Desktop\Folder\... is it possible?

[Vincenzo]

Ok for this d=dir('path');

d(i).name