http://www.perlmonks.org?node_id=998076
jospan has asked for the wisdom of the Perl Monks concerning the following question:

Oh Elders of Perldom, Wizards of Code and Masters of the Divine Editor enligthen a simple novice please! :)

I have an array (hereafter known as The Master Array).

The array is sorted.

I produce new arrays as subsets of The Master Array by using grep.

My question(s) is this:

1) will the subset arrays still be sorted as The Master Array or will I have to re-sort the subset arrays if I wish to ensure that these are sorted?

2) Whatever the answer to 1): can the answer be generalized to all cases where a function (say map) is used to produce arrays from a sorted master array?