UNIX for Dummies Questions & Answers

Hey

How do I sort an array numerically after the second column?
My values are integers like 1, 2, 3, 4... and they are not unique, so I can't just reverse my hash and sort by keys.
I wanna sort my file/array so that I get the lines with the highest value in the top - that is descending.
This is the part of my code that causes problems:

Code:

 
while (my ($accno, $count) = each %ACCcount) {    
   push ( @ACCcount, "$accno");
   push ( @ACCcount, " $count\n" );  #The space is just included because of the layout when I print the array to a file. But maybe I should push the space and newline in as separate elements and sort by column 3 instead. 
}
 
@sorted = sort { $b->[1] <=> $a->[1] } @ACCcount; 
# I also tried the following(but get the exact same warning) eventhough the order of the keys doesn't matter. They of cause just need to get sorted along with the values: 
# @sorted = sort { $b->[1] <=> $a->[1] || $b->[0] cmp $a->[0]} @ACCcount;

When I try running this I get this warning:

Can't use string ("D25304") as an ARRAY ref while "strict refs" in use at ./program line 66, <ACCIN> line 9861.

D25304 is one of the keys.

Any ideas to how to solve this problem or what is wrong with my code?

Show us the data which the %ACCcount hash is having ?

Code:

my @ACCcount = qw~123 456 7898 D1234 NN781 111 900 ZMZ ZAZ~
my @sorted = sort { substr( $a, 1, 1 ) cmp substr( $b, 1, 1 ) } @ACCcount;
print map "$_\n", @sorted;

1. you are getting the "Can't use Foo as an array ref" because "@ACCcount" is an array, not an arrayref. when you say $a->[1] you are pointing at a scalar arrayref that does not exist.

2. You Can't use the spaceship operator ( <=> ) to sort, unless all the arguments are being sorted are numeric, so you are stuck with cmp ( or a custom subroutine ).

3. Since you did not provide data I made some up, but I think this is what you want. You are sorting on the second SLOT ( slot[1] ) of each element of the array. so the first to things that are being considered for sort in the example are "2" and "5" Note: they are just considered first, that is not their final position. Can you see why?

4. Here is the output, with the data i made up, except that I bolded what determined the sort order.

Code:

900
D1234
111
123
456
7898
ZAZ
ZMZ
NN781

Hope that helps.

P.S. If you want descending reverse the positions of $a and $b.