create a zero-one matrix from non zero matrix ?

if I have a matrix A=[a b;c d] i want to convert to a matrix of zeros and ones based on the value and position of the elements in this matrix ,

if element "a" is nonzero and exists as the first element (1st row and 1st column) in matrix A then "a" to be represented in an array such that a --> [ 1 0 0 0 ] ,

b --> [ 0 1 0 0] , c --> to be [0 0 1 0] , and d --> [ 0 0 01]

so i want to make such conversion

A = [ a b

c d]

B = [ 1 0 0 0

0 1 0 0

0 0 1 0

0 0 0 1]

first array to represent element "a" is to tell that element "a" is non zero so that it have value of 1 and it is in (1 st raw, 1st column and not exists in any other location in the matrix A)

if A =[3 0

5 7]

then B=[ [1 0], [0 0] -->3

[0 0 ],[1 0] -->5

[0 0],[ 0 1] ] --> 7

and if A=[1 2 3

4 4 0

6 8 7]

to get B=[ [1 0 0 , 0 0 0, 0 0 0 ] -->1

[0 1 0 , 0 0 0 , 0 0 0 ] --> 2

[0 0 1 , 0 0 0, 0 0 0 ] -->3

[0 0 0 , 1 0 0, 0 0 0 ] -->4

[0 0 0 , 0 1 0, 0 0 0 ] -->4

[0 0 0 , 0 0 0, 1 0 0 ] -->6

[0 0 0 , 0 0 0, 0 1 0 ] -->8

[0 0 0 , 0 0 0, 0 0 1 ] ] -->7

How to do this , please?

Answer 1

[Temu]

Hi,

I tried to get this into a one-liner, but couldn't. I got close, though:

possibleChars = 'abcd';
A = 'ab0d';
B = bsxfun( @( x2, y2 ) bsxfun( @(x1,y1)(x1==y1), possibleChars, x2 ), A', 1 );
B(sum(B,2)==0,:) = [];

hth,

Temu

[AZAB]

thank u for your answer ,

Yes, this works for string elements ,

what about numeric elements such as

A=[2 4 5 0] --> B=[ 1 0 0 0 --> 2

0 1 0 0 -->4

0 0 1 0 ] ---> 5

Thaks in Advance !

AZAB

[Temu]

Just substitute the strings with numbers:

possibleChars = [2 4 5];
A = [2 4 5 0];
B = bsxfun( @( x2, y2 ) bsxfun( @(x1,y1)(x1==y1), possibleChars, x2 ), A', 1 );
B(sum(B,2)==0,:) = []

Temu

[AZAB]

Got it , Thank you it is working !

Now, I am tryign a larger scale

A=[1 2 3

4 4 0

6 8 7]

to get B=[ [1 0 0 , 0 0 0, 0 0 0 ] -->1

[0 1 0 , 0 0 0 , 0 0 0 ] --> 2

[0 0 1 , 0 0 0, 0 0 0 ] -->3

[0 0 0 , 1 0 0, 0 0 0 ] -->4

[0 0 0 , 0 1 0, 0 0 0 ] -->4

[0 0 0 , 0 0 0, 1 0 0 ] -->6

[0 0 0 , 0 0 0, 0 1 0 ] -->8

[0 0 0 , 0 0 0, 0 0 1 ] ] -->7

in this case how to define B ?

thanks in advance!