Re^3: Order in which grep/map receive elements

in reply to Re^2: Order in which grep/map receive elements
in thread Order in which grep/map receive elements

Probably because it is considered too obvious require documentation.

Things come out of map/grep in the same order they went in.

With the single exception of when grep removes item(s) from the stream, in which case those things that do come out, do so in the same relative ordering with which they went in.

With the rise and rise of 'Social' network sites: 'Computers are making people easier to use everyday'

Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.

"Science is about questioning the status quo. Questioning authority".

In the absence of evidence, opinion is indistinguishable from prejudice.

RIP Neil Armstrong

Comment on Re^3: Order in which grep/map receive elements
Re^4: Order in which grep/map receive elements by abufct (Initiate) on Oct 05, 2012 at 12:39 UTC
ok, thanks a lot! i've decided to use List::MoreUtils 'uniq', which explicitly states what I want (and uses exactly the same code I've cited in my first post).	[reply]
Re^5: Order in which grep/map receive elements by BrowserUk (Pope) on Oct 05, 2012 at 13:37 UTC
Hm So you'll use the module in preference to the code you posted because it explicitly states ordering, despite knowing that it uses exactly the same code. Erm. O-kay. With the rise and rise of 'Social' network sites: 'Computers are making people easier to use everyday' Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error. "Science is about questioning the status quo. Questioning authority". In the absence of evidence, opinion is indistinguishable from prejudice. RIP Neil Armstrong	[reply]
Re^6: Order in which grep/map receive elements by abufct (Initiate) on Oct 06, 2012 at 01:05 UTC
Yes. If (when) this code stops working because of changes in perl, there will be a bug in the library. And this bug will be fixed (in a single place). I won't have to go through all my code and find all appearances of this code and fix it. I'd write my own function for that if I didn't have that module installed on our servers already.	[reply]
Re^7: Order in which grep/map receive elements by BrowserUk (Pope) on Oct 06, 2012 at 05:03 UTC
Re^8: Order in which grep/map receive elements by abufct (Initiate) on Oct 06, 2012 at 06:05 UTC
Some notes below your chosen depth have not been shown here
Re^5: Order in which grep/map receive elements by greengaroo (Friar) on Oct 05, 2012 at 13:55 UTC
BrowserUk is right, don't use a module to do that if you can do it with one line of code! Grep receives ~~an array~~ a LIST and returns ~~an array~~ a LIST. The returned array will be shorter, but the elements will be added in the order in which they are encountered in the other array. Imagine you do this: `@array1 = @array2;` [download] The elements in @array1 will be in the same order has in @array2, right? Now do this: `foreach $element ( @array2 ) { push( @array1, $element ); }` [download] The elements in @array1 will still be in the same order has in @array2, don't you think? And if you do this: `foreach $element ( @array2 ) { if ( not $seen{$element} ++ ) { push( @array1, $element ); } }` [download] Guess what? The elements will still be in the same order and I just explicitly did what grep do in one line. There are no stupid questions, but there are a lot of inquisitive idiots. -- greengaroo	[reply] [d/l] [select]
Re^6: Order in which grep/map receive elements by abufct (Initiate) on Oct 06, 2012 at 01:22 UTC
uniq: + self describing code + behavior is guaranteed by module docs - needs a module (but I have it on our servers already) grep: - unobvious construct - behavior might change in future versions of perl (although that's unlikely) - declares auxiliary variable that might interfere with other code The choice is quite obvious to me. :-)	[reply]
Re^7: Order in which grep/map receive elements by Tanktalus (Canon) on Oct 06, 2012 at 04:11 UTC
Re^6: Order in which grep/map receive elements by jwkrahn (Prior) on Oct 06, 2012 at 06:26 UTC
Grep receives an array and returns an array. What is the difference between a list and an array? grep receives a LIST and returns a LIST.	[reply]
Re^7: Order in which grep/map receive elements by greengaroo (Friar) on Oct 09, 2012 at 18:44 UTC


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Re^3: Order in which grep/map receive elements

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