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### How do I sort a multidimensional arrays?

 on May 28, 2000 at 21:42 UTC Need Help??
Contributed by Anonymous Monk on May 28, 2000 at 21:42 UTC
Q&A  > sorting

#### Description:

I have an array of arrays which I need to sort according to the value of the second element of the anonymous arrays that are being referenced by the named array. (did that make sense?) How do I do this exactly?
```@array = [8,9,10], [4,5,6], [7,8,9];
# This is the array of arrays I need to sort
# by second elements.

# Magic step goes here....

# I need to end up with an array like @sorted:

@sorted = [4,5,6], [7,8,9], [8,9,10];

 Answer: How do I sort a multidimensional arrays?contributed by reptile ```@array = ([8,9,10], [4,5,6], [7,8,9]); @sorted = sort { \$a->[1] <=> \$b->[1] } @array [download]``` Updated and fixed thanks merlyn. Answer: How do I sort a multidimensional arrays?contributed by chromatic To expand a bit on reptile's answer, you can provide your own subroutine reference to sort. In the subroutine, \$a and \$b are provided and localized special variables used for comparing two elements to each other. In the code snippet, they're array references, and the special arrow notation is just a way of getting at the second element of each. See sort for more details. Answer: How do I sort a multidimensional arrays?contributed by tlm In answer to the somewhat more difficult question in Answer: How do I sort a multidimensional arrays?: If you seek a one-liner answer, I don't know what it is, but if you just want to get the job done, then simply transpose the matrix, apply the earlier solution (for ordering according to the n-th row elements), and then transpose back. I.e., for the general case of a non-square matrix, ```sub transpose { map { my \$j = \$_; [ map \$_[\$_][\$j], 0..\$#_ ] } 0..\$#{\$_[0]}; } my @array = ([8, 9, 10], [6, 5, 4], [7, 8, 9]); my @sorted = transpose sort { \$a->[1] <=> \$b->[1] } transpose @array; [download]``` kj Answer: How do I sort a multidimensional arrays?contributed by flope What about to sort a multidimensional array using the elements of @{\$array[1]}? ```@array = [8,9,10], [6,5,4], [7,8,9]; @sorted = [10,9,8], [4,5,6], [9,8,7]; [download]```

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 [1nickt]: heh, I hab\ve been. Trying to understand it. [1nickt]: perl -e 'print 1.0' ... output '1'. [Lady_Aleena]: You could quote it. perl -e 'print "1.0"'>/c> returns 1.0 [Lady_Aleena]: perl -e 'my \$var = "1.0"; print \$var;' if it is in a variable also returns 1.0, though perl -e 'my \$var = 1.0; print \$var;' returns 1. [1nickt]: In my case I can simply pass sprintf '%.1f', 1.0 (to Types::Standard:: Int), but what if you didn;t know the precision of the number you were working with? Seems I must be missing something. Oh well, my test list is complete, mooving on ...

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