ASCII string to binary vector in MATLAB?

Question

How do I convert a string in MATLAB to a binary vector of the ASCII representation of that string?

For example, I want to convert

string = 'Mary had a little lamb';

to a vector looking like:

[0 1 0 0 1 1 0 1 0 1 1 0 0 0 0 1, etc.]
\-------v------/ \-------v------/
        M                a

stardt · Accepted Answer · 2011-08-10 03:05:22Z

5

Do you want the entries of the array to be numbers not characters? If yes, then this should work:

s = 'Mary had a little lamb';
a = dec2bin(s,8)';
a = a(:)'-'0'

Sample output showing what this does is:

>> s = 'Ma';          
>> a = dec2bin(s,8)'; 
>> class(a)
ans =
char
>> a = a(:)'-'0'      
a =
  Columns 1 through 13
     0     1     0     0     1     1     0     1     0     1     1     0     0
  Columns 14 through 16
     0     0     1
>> class(a)
ans =
double

edited Aug 10, 2011 at 3:05

answered Aug 7, 2011 at 19:37

stardt

1,2291 gold badge10 silver badges15 bronze badges

Sign up to request clarification or add additional context in comments.

3 Comments

Bjarke Freund-Hansen Over a year ago

That would create a vector with the letters represented as their number in the alphabet, right? (Which is not what I want).

stardt Over a year ago

@bjarkef No, this creates a vector with doubles that are either 0 or 1. I have edited my response to show the output. The other answer creates a vector with chars, i.e. a string.

Bjarke Freund-Hansen Over a year ago

Great, looks exactly like what I am looking for then. :)

Egon · Accepted Answer · 2011-08-08 13:06:05Z

2

That's quite easy, but you have to know that MATLAB internally stores a string in ASCII and is able to compute with the corresponding numerical values.

So we first convert every character (number) to binary expansion (of length 8) and finally we concatenate all these cells together to your desired result.

x = arrayfun(@(x)(dec2bin(x,8)), string, 'UniformOutput', false)
x = [x{:}]

edit: As Oli Charlesworth mentions it below, the same can be done by following code:

reshape(dec2bin(str, 8)', 1, [])

edited Aug 8, 2011 at 13:06

answered Aug 7, 2011 at 18:29

Egon

4,7871 gold badge26 silver badges38 bronze badges

3 Comments

Oliver Charlesworth Over a year ago

Can't you just do reshape(dec2bin(str,8)', 1, [])?

Egon Over a year ago

@Oli Charlesworth: you can do that as well (I guess that might be a bit faster, also). I didn't know you could pass empty dimensions to reshape, which is why I hadn't given it any thought. So thank you for that!

Bjarke Freund-Hansen Over a year ago

@Egon: Do you have an example of the output corresponding to the example input string in my question?

Collectives™ on Stack Overflow

ASCII string to binary vector in MATLAB?

2 Answers 2

3 Comments

3 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

3 Comments

3 Comments

Your Answer

Sign up or log in

Post as a guest

Related