[EMAIL PROTECTED] (Adam Stern) wrote:
>Also, another question. I know perl supports array slicing, but how
>advanced does it get into it. Can it do extensive stuff like Fortran
>shown in this picture:
>http://bingweb.binghamton.edu/~head/CS471/NOTES/RUNTIME/2slice.gif
There's no built-in fanciness of the specific types shown there, but
there are always slice tricks, sometimes involving map():
Let @matrix be defined by:
@matrix = ([ 1, 2, 3, 4, 5, 6, 7, 8, 9,10],
[ 2, 3, 4, 5, 6, 7, 8, 9,10,11],
[ 3, 4, 5, 6, 7, 8, 9,10,11,12],
[ 4, 5, 6, 7, 8, 9,10,11,12,13],
[ 5, 6, 7, 8, 9,10,11,12,13,14],
[ 6, 7, 8, 9,10,11,12,13,14,15],
[ 7, 8, 9,10,11,12,13,14,15,16],
[ 8, 9,10,11,12,13,14,15,16,17],
[ 9,10,11,12,13,14,15,16,17,18],
[10,11,12,13,14,15,16,17,18,19],
);
Then the first example is:
@slice = map {[@$_[2..5]]} @matrix[3..6];
or
@slice = map {\@$_[2..5]} @matrix[3..6];
Second example (assuming you want it one-dimensional, and not a 1x5
matrix):
@slice = @{$matrix[4]}[5..9];
Third example:
@slice = map {[@$_[0..3]]} @matrix[1,3,5,7];
Fourth example:
@slice = @matrix[1,4,8];
I suspect that the fourth example is the only one you'll be truly
satisfied with. =)
Note that you can always extend data structures with different methods,
via tie() and/or overloading. So you could implement a richer slicing
behavior if you can think of how the interface should look. Then you
could even package it up as a module to share with others.
------------------- -------------------
Ken Williams Last Bastion of Euclidity
[EMAIL PROTECTED] The Math Forum
