Removing empty string elements from an Array

Spliter has asked for the wisdom of the Perl Monks concerning the following question:

I want to be able to find the empty elements in an array because I know the array I am generating will have empty elements. When I say empty elemts I mean if I print out all the elements in the array at the promt I get this:

e1
e2
         <--- this is an empty string element
e3
         <--- this is another
e4
[download]

How do I write a loop that will find these empty string elements? Then, how do I remove them from the array once I have found them?

Comment on Removing empty string elements from an Array Download Code

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Re: Removing empty string elements from an Array by Masem (Monsignor) on Nov 13, 2001 at 06:01 UTC
`@array = grep { $_ ne '' } @array;` [download] ----------------------------------------------------- Dr. Michael K. Neylon - mneylon-pm@masemware.com \|\| "You've left the lens cap of your mind on again, Pinky" - The Brain "I can see my house from here!" It's not what you know, but knowing how to find it if you don't know that's important	[reply] [d/l]
(ar0n) Re (2): Removing empty string elements from an Array by ar0n (Priest) on Nov 13, 2001 at 07:44 UTC
Taking that one step further, if by "empty" you also mean lines that consist solely of whitespace: `@array = grep /\S/, @array;` [download] [ ar0n ]	[reply] [d/l]
Re^2: Removing empty string elements from an Array by Abbot Michael (Initiate) on Mar 08, 2019 at 15:35 UTC
Masem wrote: `@array = grep { $_ ne '' } @array;` Wow, you can't improve on perfection, very cute. Long-handed its an easy problem, but clumsy because this is succinct and cute...	[reply] [d/l]
Re: Removing empty string elements from an Array by Bobcat (Scribe) on Nov 13, 2001 at 06:24 UTC
The above suggestion was great. Here's a more readable, and less efficient version: `my @newArray; foreach my $element ( @array ) { push $element, @newArray if $element; }` [download] This should push everything you want into `@newArray`. It's a bit slower than the `grep` solution, and has additional overhead of using another array; but I find it easier to read.	[reply] [d/l] [select]
Re: Re: Removing empty string elements from an Array by chipmunk (Parson) on Feb 03, 2002 at 19:37 UTC
Aside from the issue of readability, which is obviously subjective, this solution will drop any occurences of '0' from the array. A more explicit check is necessary, as in the earlier grep solutions: `my @newArray; foreach my $element ( @array ) { push $element, @newArray if defined $element and $element ne ''; }` [download] (Personally, I also prefer grep to solve this problem.)	[reply] [d/l]
Re^3: Removing empty string elements from an Array by traisjames (Initiate) on Apr 04, 2016 at 06:44 UTC
Forgive a noob, but shouldn't `push $element, @newArray` [download] be `push @newArray, $element` [download]	[reply] [d/l] [select]
Re: Re: Removing empty string elements from an Array by chip (Curate) on Nov 13, 2001 at 10:16 UTC
You call that "more readable"? Are you joking? When using any language, go with its strengths. Perl's clarity in brevity is a feature, not a bug. -- Chip Salzenberg, Free-Floating Agent of Chaos	[reply]
Re: Re: Re: Removing empty string elements from an Array by Bobcat (Scribe) on Feb 03, 2002 at 18:28 UTC
Jeez... Somebody hand me a fire extinguisher... Yes, I find it more readable. No, I'm not joking. It's about as close to plain English as you can get. It appeared to me that the questioner was not very familiar with some of the interesting nuances that separate perl from C or BASIC. When learning a language, it's often usefull to see a "here's what's happening" sort of example -- be it in pseudocode or ineffecient "straight" looping -- to show how a particular operation can happen. I'm sorry if my example offended you; I didn't intend to ruin your day.	[reply]
Re: Removing empty string elements from an Array by broquaint (Abbot) on Nov 13, 2001 at 15:32 UTC
Having not seen it listed, here's yet another way to do it `my @arr1 = ("foo", "", "bar", "", "baz"); my @arr2 = grep $_, @arr1; { $" = ', '; print "@arr1\n@arr2\n"; }` [download] Since this tests for each element in a boolean context, it will ignore any element `perl` considers to be `false`, which includes empty strings (`""`). However this also has the pitfall of dropping stuff you might want to keep e.g `qw(0 1 2) --> (1 2)`. That was the more "`perlish`" way to do it, but if you're determined to use a loop try this `my @arr1 = ("foo", "", "bar", "", "baz"); my @arr2; foreach (@arr1) { push @arr2, $_ if $_ ne ''; }` [download] HTH broquaint	[reply] [d/l] [select]

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