If by "sort a vec" you mean, treat a bitstring as a collection of n-bit values and then sort them using perl's built in sort function without converting it/them to an array, you don't. At least, not easily.

The input to sort is an array as is the return. if you bit-fields are of equal length, which is also a power of 2, then you can use vec (or unpack/pack with a pattern of '(bn)*' to convert them to/from an array.

vec( $vec, $_, 4) = rand(16) for 0 .. 99;
print map{ vec( $vec, $_, 4)} 0 .. 99;

 6 15  0 10  4  6 10  1 13  9 
 7  1  1  1  7 12  3  6 14  7 
 4  7  8  7  0  4 10  0 13  6  
 6  9 14  7 10  5 12  4 15 11 
13 12  7  2 13 14  4  7  0 10
 9  4 10  5  3 12 10  9 15 12 
 5  3  8  0  0  6  7  0  2 14 
14  1  3 13  4 15  8 10  2  8 
11  2  0 14 10  4  8  6 10  1 
10  7 10 13  6  5 12  6  0 15
 
$p=0; 
map{ vec( $vec, $p++, 4) = $_ } 
sort{ $a <=> $b } 
map{ vec( $vec, $_, 4) } 0 .. 99;

print map{ vec( $vec, $_, 4)} 0 .. 99;
 0  0  0  0  0  0  0  0  0  1
 1  1  1  1  1  2  2  2  2  3
 3  3  3  4  4  4  4  4  4  4
 4  5  5  5  5  6  6  6  6  6 
 6  6  6  6  7  7  7  7  7  7
 7  7  7  7  8  8  8  8  8  9
 9  9  9 10 10 10 10 10 10 10
10 10 10 10 10 11 11 12 12 12
12 12 12 13 13 13 13 13 13 14 
14 14 14 14 14 15 15 15 15 15
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It would be possible supply sort with a list of integers 0 to the length (in bitfields) of your vector and to play games inside the sort block, performing the switching of the bit-strings yourself using vec and returning the approriate value (-1, 0, 1) yourself to indicate what you had done. This is difficult to get right, fragile as heck, and grossly inefficient as the convertion for testing would be done for every comparison of every field, rather than just once at the beginning and once at the end. Nothing more than an intellectual curiosity. I probably shouldn't have even mentioned it:)

Thanks, for your help. I appreciate it. I am trying not convert the vec to an array because I don't have that much memory. I created a couple different sorting functions where I do switch the bitstrings myself. I used the algorithms for insertion, substitution and quicksort just to do a comparison on which one would be the best for this type of problem. Insertion and substitution are really slow once I try to sort a vec of a million integers which makes sense but I had to try. Quicksort right now is giving me problems, I think due to recursion but I am not certain. I was hoping there was clever way to do it within Perl. I wanted to say thanks for the help!

Your welcome, but if you gave us a little more information, we could probably suggest a better solution.

For example, how many bits are in each of your integers?

How many do you need to sort?

Storing a million integers in a standard perl array and sorting them is an almost everyday procedure. Even on my 233Mhz laptop it takes less than five minutes using perls builtin sort. So, unless you have a very large number, or the integers are very large, the standard sort would probably suffice.

If you have a very large number of small integers, say 100_000_000 x 8-bits or less, or 1_000_000 x say 128 bit, this could still be done with a custom sort routine without too much trouble.

Knowing what your requirements are would allow someone here to suggest a solution.

---

Examine what is said, not who speaks.
"Efficiency is intelligent laziness." -David Dunham
"Think for yourself!" - Abigail
Hooray!
Wanted!

When you say "sort a vec", do you mean something like: given an input bit sequence "01001010", the output sequence should be "00000111"?

If that's what you mean, and the homework assignment is to do this without using "sort", you could think of the problem as simply counting the number of set bits in the input vec, and setting that many low-order bits in the output vec.

To do this, you'd want the C-like '&' operator to test bits, the '|=' assignment operator to set bits, and the '<<' operator to position a given set bit. The "perlop" man page will explain their uses.

No, I mean a vec like "5583950372654" and I want to sort it to "02345556789". I have a file of integers that I am putting into a vec because an array will not fit them all. I actually then need to sort this vec based on values of another vec. But regardless of that, I was curious if there was a more 'perl' way to sort a vec but without converting it to an array first because of memory problems. I can do this through creating my own sort function and have done using insertion, substitution and quicksort (just to see which was truely better) but I was curious if there was another way to do this. No, not a homework assignment unfortunetly :)

Okay, I'll confess I'm no whiz at using bit vectors in perl, but I still find your question confusing, and I think you need to provide more information (or be more careful about what you're trying to say). In your example, it looks like the output of the sort is shorter than the input, but the truncation is inconsistent: the input has a couple of "3"s, where the output has one "3"; the input has four "5"s, where the output has three of them.

How many bits make up each element of the bit vector string?

If your real goal is to sort the integer values in one big file based on the integer values in some other big file, there are probably better ways to do this than trying to cram all that data into memory as bit vectors. But I wouldn't hazard a guess about that, since I still don't quite get what you're after.

(For that matter, if you have already solved the problem by other means, and are just fishing for some different way to do it, that still strikes me as being more like homework, even if you aren't doing it for a grade.)