Converting integer values to logical array

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Najiya Omar
Najiya Omar 2016-12-17
评论： Carlos Orduno 2021-9-3
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.

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采纳的回答

Image Analyst
Image Analyst 2016-12-17
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')
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Carlos Orduno
Carlos Orduno 2021-9-3
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')

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更多回答（3 个）

Steven Lord
Steven Lord 2020-8-28
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 2019-10-14
编辑：Anthony Bartoletti 2019-10-14
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 2020-8-28
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.

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