Delete elements from array if they contain some string

Question

Lets say I have an array with following data:

@array[0] = "hello this is a text"
@array[1] = "this is a cat" 
@array[2] = "this is a dog"
@array[3] = "this is a person"
@array[4] = "this is a computer"
@array[5] = "this is a code"
@array[6] = "this is an array"
@array[7] = "this is an element"
@array[8] = "this is a number"

I want to have a loop where it goes through all the array elements and finds out if any of the elements have the value "dog" in them if the element does have dog, then delete the element. and so results would be :

@array[0] = "hello this is a text"
@array[1] = "this is a cat" 
@array[2] = "this is a person"
@array[3] = "this is a computer"
@array[4] = "this is a code"
@array[5] = "this is an array"
@array[6] = "this is an element"
@array[7] = "this is a number"

@var[index] = ... is bad style. Use $var[index] = .... This expression uses the $ sigil, but still refers to the named array @var. See perldata. — mob
– mob, Commented Jun 20, 2013 at 15:17

mob · Accepted Answer · 2015-09-01 18:29:00Z

14

~~@array = grep not /dog/, @array;~~

@array = grep !/dog/, @array;

edited Sep 1, 2015 at 18:29

answered Jun 20, 2013 at 15:14

mob

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2 Comments

David Poole Over a year ago

v5.16.3 gives me a error "not enough arguments for grep" The "not" should be a "!" perhaps? (Another answer is using !)

mob Over a year ago

Sorry David, not has different precedence than !

ysth · Accepted Answer · 2013-06-20 19:16:06Z

9

Clearly just reassigning the whole array is easier, but to actually loop through and delete, you do something like this:

use strict;
use warnings;

my @array = (
    'hello this is a text',
    'this is a cat',
    'this is a dog',
    'this is a person',
    'this is a computer',
    'this is a code',
    'this is an array',
    'this is an element',
    'this is a number'
);

for my $index (reverse 0..$#array) {
    if ( $array[$index] =~ /dog/ ) {
        splice(@array, $index, 1, ());
    }
}

print "$_\n" for @array;

output:

hello this is a text
this is a cat
this is a person
this is a computer
this is a code
this is an array
this is an element
this is a number

edited Jun 20, 2013 at 19:16

answered Jun 20, 2013 at 15:41

ysth

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1 Comment

ysth Over a year ago

$#array is the index of the last element of @array (or -1 if it is empty)

khr055 · Accepted Answer · 2013-06-20 15:53:54Z

8

@array = grep(!/dog/, @array);

edited Jun 20, 2013 at 15:53

khr055

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answered Jun 20, 2013 at 15:36

capiggue

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2 Comments

dataminer123 Over a year ago

does this delete the element also?

capiggue Over a year ago

Yes. You could print the elements (or element counts) before and after this operation to see the difference.

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