Creating a hex array with 4 digit blocks from an array of integers

I am using R2013 and need to convert a large decimal array into hex stings.

The decimal numbers can be any positive integer, and I need to convert each number, then display each as a minimum two byte string with preceding zeros (with more bytes shown as the number increases).

e.g. decimal "1" should show up as '0x0001',

decimal "69876" should show up as '0x0001 0x10F4'

I created a rather cumbersome loop that does this perfectly, but with large arrays it takes too long.

I can get part way to a non-loop implementation with this code:

DecArray = [1 2 4 69876];
cellstr(dec2hex(reshape(DecArray,[],1), 4));
ans = 
    '00001'
    '00002'
    '00004'
    '110F4'

But as you see the outputs

1) always have the same number of digits, and

2) aren't broken into 2 Byte blocks

Is there any way to go from these results to the ones I described earlier without another loop?

[Walter Roberson]

How would the output be interpreted? If you have

0x0001 0x10F4

as output, then how would someone or a program reading it know whether that should be 1 followed by 4340 or should be interpreted as the pair 69876 ?

[Art]

What I'm doing is creating an array of YTickLabels. I have a button on my figs that changes the YTickLabels from Dec to Hex, and it will only be read by people who <should :-) > understand what they are seeing.

[Walter Roberson]

They can read hex, but only if it is broken up into words in that particular format??

[Art]

The data can be in 16bit OR 32bit words, so it's just a matter of displaying in the easiest way to read for the data being analyzed. If the dec number is greater than 65535 then it's a 32 bit and should display as such.

[Walter Roberson]

I dunno. It just seems unlikely to me that the data could vary between 16 and 32 bits on the same plot.

Answer 1

[Stephen23]

V = [1,2,4,69876];
L = log(16);
for k = 1:numel(V)
    N = 4*(1+fix(log(V(k))/L/4));
    S = sprintf('%0*X',N,V(k));
    Z = sprintf('0x%c%c%c%c ',S)
end

Prints this in the command window:

Z =
0x0001 
Z =
0x0002 
Z =
0x0004 
Z =
0x0001 0x10F4

Note: does not work for zero: add N = max(4,N)

[Art]

Stephen,

This works great and is much simpler than my old loop. If I can't get Guillaume's answer to work then I will accept this. Thanks!

Answer 2

[Guillaume]

DecArray = [1 2 4 69876]';
h = arrayfun(@dec2hex, DecArray, 'UniformOutput', false);
cellfun(@(s) strcat('0x', cellstr(reshape([repmat('0', 1, mod(-numel(c), 4)), c], 4, [])')), d, 'UniformOutput', false)

[Art]

Guillaume,

I think this is what I want, but there is an error somewhere. I get

"Undefined function or variable 'd'. "

Where is 'd' coming from?

Thanks in advance

[Walter Roberson]

d should be h

[Art]

I had to substitute h for both d and c, but the output format wasn't quite what I needed.