Allocating first and last rows from column 2 that correspond to specific criteria in column 1 in a for loop to a new matrix or submatrix

I have a binary matrix consisting of 10100 x 15 elements where elements==1 are grouped in n sequential rows per column and their index differs in each column. For example

X =

1 0 0 0

1 1 1 0

1 1 1 1

0 1 1 1

0 0 0 1

What I aim to do, is to replace the 10100 rows per each column with the the first and last indeces of value==1. Thus in each column I should only have 2 rows representing the indeces of interest.The final output should be a matrix that looks something like that:

Index_X=

1 2 2 3

3 4 4 5

Please let me know if there is a neat way to obtain the indeces of rows/col of the main matrix X. This is the code I'm currently using and it is not giving me what I want:

for j=1:15; %15 is the total number of columns in the original matrix
    
    %....code to obtain X matrix 10100x15
    
    [row col]=find(ismember(X,1));
    concatenate_colrow=cat(2,col,row);  % this yields indeces of columns ==1 in original matrrix in (:,1) and indeces or adjacent rows in (:,2)
    
%.....should I do something here to obtain the rows indeces==1 and placing as in example above?????
end

Thank you

Answer 1

[Stephen23]

X = [1,0,0,0;1,1,1,0;1,1,1,1;0,1,1,1;0,0,0,1];
N = size(X,2);
Y = nan(2,N);
for k = 1:N
    V = find(X(:,k));
    Y(:,k) = V([1,end]);
end

giving

Y =
   1   2   2   3
   3   4   4   5

[Lina Koronfel]

Thank you so much for your reply. I'm getting this error message though and I'm not sure why I'm getting it:

Array indices must be positive integers or logical values.

Error in CODE (line 93)

Ywhatever(:,k)=LED_rowcol_index([1,end]);

This is how I'm implementing the code you recommended. I also get the same error if implemented inside the first for loop (j):

for j=1:15
    %....code to obtain X matrix 10100x15
end

BinarySize=size(X,2);
Ywhatever=nan(2,BinarySize);

for k =1:BinarySize
    LED_rowcol_index=find(X:,k));
    Ywhatever(:,k)=LED_rowcol_index([1,end]);
end

[Stephen23]

find(X(:,k))
%     ^ your code is missing this parenthesis

[Lina Koronfel]

Oh sorry that was a typo while copying. However, I realized what the issue is. The first 2/15 columns are lacking value==1. Thus the find function yielded an empty array that could't be processed by the following line Ywhatever(:,k)=LED_rowcol_index([1,end]);.

I changed the for loop to start from 3 instead of 1 and now it is working.

for k =3:BinarySize
    LED_rowcol_index=find(X:,k));
    Ywhatever(:,k)=LED_rowcol_index([1,end]);
end 

[Lina Koronfel]

Thanks for your answer though. You saved my day!!