MATLAB: How to find the position of a number in an array

array

If I have a vector, a = [7 8 8 2 5 6], how do I compute the positions of the value 8?
I expect 2 and 3 or (1,2) and (1,3).

Best Answer

You can use the “find” function to return the positions corresponding to an array element value. For example: 
a = [7 8 8 2 5 6]; 
linearIndices = find(a==8) 
 
linearIndices = 
     2     3
To get the row and column indices separately, use: 
[row,col] = find(a==8) 
 
row = 
     1     1 
 
col = 
     2     3
If you only need the position of one occurrence, you could use the syntax “find(a==8,1)”. You can also specify a direction if you specifically want the first or last occurrence, such as “find(a==8,1,’first’). For more information on these options, see “find”.
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