MATLAB Answers

Converting integer values to logical array

85 views (last 30 days)
I have a vector (160,1) in size which include integer number from 1 to 4, I want to convert in logical array by replacing 1 to(1 0 0 0), 2 to (0 1 0 0), and so on; for classifiction propblem.

Accepted Answer

Image Analyst
Image Analyst on 17 Dec 2016
Try this:
m = randi([1, 4], 160, 1)
% Get 3 bit array
characterArray = dec2bin(m)
% Tack on column of 0's to the left edge
characterArray = [repmat('0', 160, 1), characterArray]
logicalArray = logical(characterArray - '0')
  5 Comments
Carlos Orduno-Albarran
Carlos Orduno-Albarran on 3 Sep 2021
Thanks for sharing,
This solution gave an error, so I modified it slighly, just in case someone is having any problem.
% Generate random values
m = randi([1, 4], 160, 1)
% Get 4 bit array
characterArray = dec2bin(m,4)
% convert to logical array
logicalArray = logical(characterArray - '0')

Sign in to comment.

More Answers (3)

Steven Lord
Steven Lord on 28 Aug 2020
You can use implicit expansion.
>> r = randi(4, 10, 1); % Your values will vary
>> values = r == 1:4;
>> t = table(r, values)
t =
10×2 table
r values
_ __________________________
1 true false false false
2 false true false false
3 false false true false
4 false false false true
4 false false false true
1 true false false false
4 false false false true
4 false false false true
2 false true false false
4 false false false true

Anthony Bartoletti
Anthony Bartoletti on 14 Oct 2019
Edited: Anthony Bartoletti on 14 Oct 2019
I'm not sure this is the answer requested. The solution given turns
1 into ( 1 0 0 0 ), 2 into ( 0 1 0 0 ), 3 into ( 1 1 0 0 ), 4 into ( 0 0 1 0 ).
But for a classification problem, you want to turn
1 into ( 1 0 0 0 ), 2 into ( 0 1 0 0 ), 3 into ( 0 0 1 0 ), 4 into ( 0 0 0 1 ).
I managed a solution: Create a logical 4x4 identity matrix with I = logical(eye(4)). Then given a sequence (row) r of integers 1 <= n <= 4, conduct
M = I( :, r)
This will select from the 4 logical basis vectors as columns, according to the sequence r.

Deryck Chan
Deryck Chan on 28 Aug 2020
I've combined the two approaches above and came up with this rather elegant solution:
% Example input
y = [1 3 4 5 7 9 8 2 1 5 10 3 4 6 8 2 6 1 2 7 10];
num_labels = max(y)
% Convert y into y_matrix
logic_template = eye(num_labels);
y_matrix = logic_template(:, y);
You can use boolean(eye(num_labels)) instead of eye(num_labels) if you want the result to be in the logical datatype.

Tags

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!