Re^3: filtering an array

[philiprbrenan]

in reply to Re^2: filtering an array
in thread filtering an array

You are using a variable in a pattern matching regular expression and said variable currently has no value. Please try assigning a value to the variable and see what happens. Thanks.

[prbndr]

i see. so if my array @positions is already defined and created, do i need to loop over all the values in @positions and then execute the code you posted?

something like:

 for (@positions) {@positions = grep $_->[1] =~ /ac/i, @positions;}

and then:

 for (@positions) {@positions = map $_->[0], @positions;}

[philiprbrenan]

You do not need the for becuase grep loops over the array you give it. Please change:

 
 for (@positions) {@positions = grep $_->[1] =~ /ac/i, @positions;}

to:

 
 @positions = grep $_->[1] =~ /ac/i, @positions;

[prbndr]

right, but the error still persists. what here isn't defined?

[philiprbrenan]

Likewise, the for is unnecessary in this code too:

for (@positions) {@positions = map $_->[0], @positions;}

It should just be:

@positions = map $_->[0], @positions;

because map iterates over the array you give it. Even better, you could write:

$_ = $_->[0] for @positions;

here we are making the for implicit in map explicit.

[prbndr]

perl still has a problem with this:

@positions = grep $_->[1] =~ /ac/i, @positions;

with the same error Use of uninitialized value in pattern match (m//)