How to find what number is missing from a range inside of an array?

I wanted to know if there was anyway to get matlab to tell me what number was missing from an array of numbers? Kind of like a sudoku problem, I wanted to have matlab look at each row or column in an array and tell me what number from a range of numbers is missing. So, for example, if my array looks like this:

x = 5x5 array

 [1 2 0 4 5
  2 0 3 4 5
  4 5 1 0 2
  0 3 4 5 1
  1 0 4 3 5]

The numbers in the array can be in any particular order, I just threw this one together for example. In this example, each row is made of elements of numbers on a range 1:5, with zero being the number that is missing from each row within that range. I know how to find all the indices outside of the range 1:5, but I wanted to know if there was a way to return what values are actually missing from each row? So, for example, I wanted to know if I can get matlab to tell me something like,

ans = 5x1 array
    [3
     1
     3
     3
     2
     2]

So these are the numbers that are missing from each row. Can I get matlab to do this?

Answer 1

[Adam Danz]

Check out Lia = ismember(A,B)

Example

full = [1;2;3;4;5]; 
sample = [2;4;5];
idx = ismember(full, sample);
full(~idx)

[Brett Baxter]

I'm trying to apply this to the above array x and it's not returning the missing values. Could you help me better understand?

[Adam Danz]

Sure, let's see what you tried so I can help fix it.

[Brett Baxter]

x = [1 2 0 4 5
  2 0 3 4 5
  4 5 1 0 2
  0 3 4 5 1
  1 0 4 3 5]

So first I put in the value of x

full = [1;2;3;4;5]

Then I put in the range of numbers that should be in each row

idx = ismember(x, full)

idx =

  5×5 logical array

   1   1   0   1   1
   1   0   1   1   1
   1   1   1   0   1
   0   1   1   1   1
   1   0   1   1   1
   

Then I had it check to see which were in the range of numbers

But now when I try x(~idx) or full(~idx) it doesn't return what values from the range are missing in each row.

[Adam Danz]

The two input terms are in different order than in my answer. That matters!

Also, my answer works with vectors while yours contains a vector and a matrix.

ismember(A,B) returns a logical array the same size as A where "true" indicate that the elements of A are anywhere in B.

If you're performing this operation on columns of a matrix, loop through the columns so you're also working with vectors.

[Brett Baxter]

okay, so I need it to check each row or column individually? Like, I need to have row 1 be a vector, then row 2, then 3 etc?

[Adam Danz]

If you want to know which elements in A are missing in the entire matrix, use

ismember(ColumnVector, matrix(:))

If you want to know which elements are missing in each row or column you'll need to loop through the rows/columns.