location of logical matrix

Hi I have a 10 x 2 logical matrix and I would need to find out the location of the rows which both columns are ones i.e 1 1.

May I know how I may write for this? Thank you!

Answer 1

[madhan ravi]

Since you have a logical matrix it’simply:

ix=all(matrix ,2); % logical indexing is efficient
  Wanted=find(ix)

[Cside]

oops that only gave me a list of numbers 1 - 10, without the criteria of both columns being ones

[Walter Roberson]

matrix(ix,:)

however we can already predict that the result would just be a variable number of rows with both columns being 1, so this is not of interest. What is of interest is either the logical row mask, ix, or else the numeric row indices, which are in Wanted.

madhan's code is correct.

[Cside]

I would like to find the position of the rows that fit the criteria, and have it presented in a vector. perhaps I was slightly vague in my question, still learning! :)

[madhan ravi]

Thank you , sir Walter.

>> matrix

matrix =

  4×2 logical array

   1   1
   0   1
   1   0
   0   1

>> ix=all(matrix ,2)

ix =

  4×1 logical array

   1
   0
   0
   0

>> Wanted = find(ix) % this is what you want

Wanted =

     1

>> matrix(ix,:)

ans =

  1×2 logical array

   1   1

>> 

[Cside]

thank you madhan for being so clear with your answer :)

[madhan ravi]

While learning always visualize with a simple and short example to understand what's going on.

Answer 2

[KSSV]

Read about ismember

idx = round(rand(10,2)) ; 
vec = [1 1] ; 
[c,ia] = ismember(idx,vec,'rows') ; 
iwant = find(c) ;
idx(c,:)
idx(iwant,:)