MATLAB: How to create logical binary matrix where two variables are from the same row

binary matrixlogical index

Hi .. let's say I have this table
*X*     *Y*
01       a
01       b
01       c
02       b
02       g
03       a
03       g
04       a
04       b
04       c
I want to create a logical binary matrix where the rows indicate to the unique values of X and the columns indicate the unique values of Y the output would be like this
      a    b    c    g
  01  1    1    1    0
  02  0    1    0    1
  03  1    0    0    1
  04  1    1    1    0
I have a large table and I want to find groups of Xs based on Ys. According to this example, I have 3 groups (01,04) (02) (03).
any help would be appreciated thank you

Best Answer

You could use unique and sub2ind:
V = [1,1,1,2,2,3,3,4,4,4];
C = {'a','b','c','b','g','a','g','a','b','c'};
%
[Cu,~,Cc] = unique(C);
[Vu,~,Vr] = unique(V);
out = false(numel(Vu),numel(Cu));
out(sub2ind(size(out),Vr,Cc)) = true
Creates:
>> out
out =
     1     1     1     0
     0     1     0     1
     1     0     0     1
     1     1     1     0
>> Cu % columns
Cu = 
    'a'    'b'    'c'    'g'
>> Vu % rows
Vu =
     1     2     3     4
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