Coder Structure element Size Mismatch error during subscripting

Hi

I am facing Size mismatch error while performing array operation with structure .I need help in resolving the issue

Impnse.isOut(:,idx) = memfcn(1:size(Impnse.f(:,idx),1),locs);

Error Message : Size mismatch ([441000 x 1] ~= [:? x 441000])

f = zeros(441000, 2)

isOut = zeros(size(f,1),2);

Input Impnse = struct('f',f ,'isOut' ,isOut);

Impnse.isOut(:,idx) = memfcn(1:size(Impnse.f(:,idx),1),locs);
size(1:size(Impnse.f(:,idx),1))
ans =
           1      441000
size(locs)
ans =
        1423           1
size(Impnse.isOut(:,idx))
ans =
      441000           1
Size mismatch ([441000 x 1] ~= [:? x 441000])

[Adam Danz]

What is the size of the output?

x = memfcn(1:size(Impnse.f(:,idx),1),locs)
size(x)

[Jogger]

K>> x = memfcn(1:size(Impnse.f(:,idx),1),locs);
K>> size(x)

ans =

           1      441000

[Jogger]

With modified setting , I still observe the error

Modified Input 
isOut     = false(2,size(f,1));
size(memfcn(1:size(Impnse.f(:,idx),1),locs))
           1      441000

K>> size(Impnse.isOut(idx,:))
ans =
           1      441000
class(Impnse.isOut)
    'logical'

class(Impnse.f)
    'double'

x = (memfcn(1:size(Impnse.f(:,idx),1),locs));
size(x)
ans =
           1      441000
class(x)
ans =
    'logical'
Erorr message:Size mismatch ([1 x 441000] ~= [:? x 441000]).

[Adam Danz]

I'm guessing that you need,

Impnse.isOut(idx,:) = memfcn(1:size(Impnse.f(:,idx),1),locs);
%            ^^^^^

[Jogger]

Yes, that's correct but how - is not clear to me

[Adam Danz]

Addressed below in my answer.

Answer 1

[Adam Danz]

Impnse.isOut(idx,:) = memfcn(1:size(Impnse.f(:,idx),1),locs);
%            ^^^^^

This is matrix indexing 101 and it's a rudimentary concept to understand.

The size of your output is 1 x 441000 which means it's a row vector with 441000 elements.

The output Impnse.isOut(idx,:) means that you're storing the 441000 values in the row number defined by idx.

For example,

a = zeros(3,6)
a =
     0     0     0     0     0     0
     0     0     0     0     0     0
     0     0     0     0     0     0
     
a(2,:) = 1:6  
     0     0     0     0     0     0
     1     2     3     4     5     6
     0     0     0     0     0     0

With Impnse.isOut(:,idx), you're storing the values in the column number defined by idx.

If the matrix does not have 441000 rows, the data won't fit.

For example,

a = zeros(3,6)
a =
     0     0     0     0     0     0
     0     0     0     0     0     0
     0     0     0     0     0     0
     
a(:,2) = 1:6  

Error: 
Unable to perform assignment because the size of the left side is 3-by-1 
and the size of the right side is 1-by-6. 

However, if the matrix does have the right amount of rows, the data can be transfered to the column even if it's a row vector.

 a = zeros(6,3)
a =
     0     0     0
     0     0     0
     0     0     0
     0     0     0
     0     0     0
     0     0     0

a(:,3) = 1:6
a =
     0     0     1
     0     0     2
     0     0     3
     0     0     4
     0     0     5
     0     0     6

I don't know why your error message differs. Perhaps you're using a different version of matlab or perhaps the error message is customized.

[Jogger]

Thanks a lot for the help! I did further analysis and have observation. Since we are dealing with logical structure , I added addtional stuff in a small script

a = zeros(3,6) % row,col

% Test purpose
num_row = 2;
num_col = 2;
len_col = size(a,2);
len_row = size(a,1);
len_size_row = 1:size(a,1);
len_size_col = 1:size(a,2);

% evaluation
% store the coloumn values in the row's wise
% Impnse.isOut(idx,:)
a(num_row,1:len_col) =  1:len_col        % data values
a(num_row,1:len_col) == 1:len_col        % all logical index
a(num_row,num_col)   == 1:len_col        % logical index of num_col
a(num_row,num_col)   =  len_col          % data values 
a(len_row,num_col)   =  len_col          % data values 


%Error case 
a(len_row,num_col)   =  1:len_col;        % data values 
% Unable to perform assignment because the size of the left side is 1-by-1 and the size of the right side is 1-by-6.

a(len_size_row,num_col)   =  1:len_col;        % data values 
% Unable to perform assignment because the size of the left side is 3-by-1 and the size of the right side is 1-by-6.

a(num_row,num_col)   =  1:len_col;        % data values 
% Unable to perform assignment because the size of the left side is 1-by-1 and the size of the right side is 1-by-6.

% store the coloumn values in the row's wise
% Impnse.isOut(:,idx)
a = zeros(3,6) % 3row,6col
a(:,num_col) 
a(:,num_col) = 1:3        % values
a(:,num_col) == 1:3       % logical index
a(:,num_col) == 1:6       % logical index

% Erorr -case 
a(:,num_col) = 1:6       % logical index
% Unable to perform assignment because the size of the left side is 3-by-1 and the size of the right side is 1-by-6.

% change row's to support num coloumns
a = zeros(6,3) % 3row,6col
a(:,num_col)= 1:6       % values
a(:,num_col)== 1:6      % logical index

If Implementation is like below , then it is not doing the intended job

   s_data = memfcn(1:size(Impnse.f(:,idx),1),locs);
    Impnse.isOut(:,idx) = 1:size(s_data,2); % use  repmat(data,row,col)

I don't know why your error message differs. Perhaps you're using a different version of matlab or perhaps the error message is customized.

My version : '9.7.0.1319299 (R2019b) Update 5'

Note : a = zeros(3,6)

a(:,2) = 1:6

The missing part and my understanding

"This is copy index location i.e. starting 1 to 6 but I am looking for the values from 1 to 6 index in the row for a column number."

1:6 is range for copying the data but data in the range is not copied. ONLY range number are copying instead of range(data)

My problem is resolved if following way coding is done

   s_data = memfcn(1:size(Impnse.f(:,idx),1),locs);
    Impnse.isOut(:,idx) = s_data(:); % use  repmat(data(:),row,col)

Please confirm if my understanding is right ? Thank you

[Adam Danz]

When I test the block of code you shared using r2019b update 6, it produced an error on this line

a(len_row,num_col)   =  1:len_col;        % data values 

Error: 
Unable to perform assignment because the size of the left side 
is 1-by-1 and the size of the right side is 1-by-6.

This is because len_row=3 and num_col=2 but 1:len_col=[1,2,3,4,5,6]. So, you're trying to put 6 values into a space of 1-value.

I didn't understand what I'm supposed to confirm. Instead of trying to explain it again, I recommend spending an hour or so reading through this page and practicing indexing. Indexing is an important thing to understand if you're going to use matlab. Once you understand this page, you will be able to solve this.

[Jogger]

Hi Adam,

I went through the this page and found interesting tricks. I found Shifting the Rows of a Matrix very interesting.

For the implementation point of view , below logic is solving the size mismatch error

   s_data = memfcn(1:size(Impnse.f(:,idx),1),locs);
    Impnse.isOut(:,idx) = s_data(:); % copy rows in the respective column number

Thank you very much for guidenace and help!

[Adam Danz]

Nice work!

[Jogger]

Hi Adam,

Can you please help me with below link issue ?

Thank you!

https://www.mathworks.com/matlabcentral/answers/608261-alternate-way-without-ismember-function

[Jogger]

Hi Adam,

Can you please help me with below issue resolution

https://www.mathworks.com/matlabcentral/answers/626663-find-sorrunding-elements-and-element-from-a-array

Most relavent section from above problem is in the below link

https://www.mathworks.com/matlabcentral/answers/626663-find-sorrunding-elements-and-element-from-a-array#comment_1089498

Thank you!