Problems with changing the order of a binary representation

Hello everyone,

I have a problem to organize a binary representation that I calculate in Matlab, like this:

NJ=3

for i = 1:2^NJ-1

struct(i,:) = dec2bin(i,NJ);

end

This gives me this result:

ans:

struct =

7×3 char array

'001'

'010'

'011'

'100'

'101'

'110'

'111'

The problem is that I need this binary representation to have the following order:

100

010

110

001

101

011

111

I really need this to be done by the code because if you increase the number in NJ, it is no longer practical to do the manual change, as the amount of struct data increases exponentially.

I appreciate any help, Thank you.

[Clayton Gotberg]

I noticed that you've changed the list from a character array to plain numbers. Do you also need the output to be plain numbers? If so, you can use str2double to convert the characters into numbers.

[Jennifer Arellana]

Yes, I changed it because I noticed that I had not put the correct data, but I also wanted to try to convert from characters into numbers but when I tried it I got the following result:

>> a = str2double(B_ampl)

a =

Inf

I don't understand why.

[Clayton Gotberg]

what is B_ampl? If it's your replacement for struct, the problem is probably with the formatting of the input. If you input a simple char array, the function assumes you're giving it one number. If you input a string array or a cell array containing char arrays, the function can see the numbers separately.

Answer 1

[Clayton Gotberg]

Use the fliplr function to swap the direction of arrays!

NJ=3
for i = 1:2^NJ-1
    binary_save(i,:) = fliplr(dec2bin(i,NJ));
end

I also changed the name of struct to binary_save because struct is the name of a built-in MATLAB function, and it's best to avoid accidentally overwriting MATLAB functions. For example,

input = ones(5,4); % A 5x4 matrix
size = 3; % Setting the size for something later

for k = 1:size(input,1)
    % Some operation
end

Will run from k = 1:3 instead of k = 1:5 (the number of rows in the input) and

input = magic(5);
size = 3; % Setting the size for something later

for k = 1:size(input,1)
    % Some operation
end

Gives an error about how the index in position 1 doesn't make sense but doesn't even tell you in which line it's occured.

[Paul Hoffrichter]

didn't see your post.

[Clayton Gotberg]

I hope Mathworks will eventually be able to send alerts about new answers to posts you're currently viewing. I've done the same thing at least 3 times this week!

[Paul Hoffrichter]

I will start hitting "follow" to get timely alerts. Not perfect since emails take time to arrive depending upon the email service.

Answer 2

[Paul Hoffrichter]

NJ=4
for i = 1:2^NJ-1
    struct(i,:) = fliplr(dec2bin(i,NJ));
end

struct =
  15×4 char array
    '1000'
    '0100'
    '1100'
    '0010'
    '1010'
    '0110'
    '1110'
    '0001'
    '1001'
    '0101'
    '1101'
    '0011'
    '1011'
    '0111'
    '1111'