Re: Array looping

Rather than walking the arrays, use join and xor the joined strings, counting nuls with tr.

johngg@shiraz:~/perl/Monks > perl -Mstrict -Mwarnings -E '
my @arr1  = qw{ A T C G T C G A G C G };
my @arr2  = qw{ A C G T C C T G T C G };
my $count =
   ( ( join q{}, @arr1 ) ^ ( join q{}, @arr2 ) ) =~ tr{\0}{};
say $count;'
4
[download]

I hope this is of interest.

Cheers,

JohnGG

Comment on Re: Array looping Select or Download Code

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Re^2: Array looping by vrk (Chaplain) on Apr 12, 2017 at 15:01 UTC
That's interesting. I hardly ever think of using the string xor operator. Surely your solution can be golfed, though... `$ perl -alpE '$_=($F[0]^$F[1])=~tr{\0}{}' ATCGTCGAGCG ACGTCCTGTCG 4 ^D` [download]	[reply] [d/l]
Re^3: Array looping by johngg (Canon) on Apr 12, 2017 at 16:53 UTC
Well, since the OP's post started with arrays rather than strings your golf is cheating slightly ;-) However, if the problem comes from the real world I think the odds are better than even that the OP started with strings and split them into arrays in order to do the comparison. In that scenario your golf is fine, though anything other than "snippet" dna strings are unlikely to fit on the command line! Cheers, JohnGG	[reply]
Re^4: Array looping by vrk (Chaplain) on Apr 13, 2017 at 08:11 UTC
Oh, it will work with file input too since it's reading from stdin. Just make sure the two sequences are separated by a space.	[reply]
Re^3: Array looping by Anonymous Monk on Apr 12, 2017 at 22:42 UTC
32 strokes: `$ perl -pale '$_^=$F[1];$_=y/\0//' ATCGTCGAGCG ACGTCCTGTCG 4` [download]	[reply] [d/l]
Re^4: Array looping by vrk (Chaplain) on Apr 13, 2017 at 08:12 UTC
Brilliant!	[reply]
Re^3: Array looping by james28909 (Deacon) on Apr 13, 2017 at 11:55 UTC
Do you all know of a good place I can study or learn about these short/compact functions? Is it called perl golf? What is perl golf?	[reply]
Re^4: Array looping by afoken (Chancellor) on Apr 13, 2017 at 14:16 UTC
Do you all know of a good place I can study or learn about these short/compact functions? Is it called perl golf? What is perl golf? Re^3: Golf code in perl (Context) And no, please don't use "golfed" code for any other purpose than to play golf. It's simply unmaintainable in that form, write-only code in its purest form. Prefer writing longer, readable code that you (or any other maintainer) will still understand in half a year, a year, or five years. If you resort to "dirty tricks" (like string xor plus counting NUL bytes), add a comment that explains how the trick works and the requirements for that trick (e.g. strings must only contain ACGT, all upper case, both the same length, etc). Don't make your future self invent a time machine to come back and severely hurt you for the mess you will have written. Alexander -- Today I will gladly share my knowledge and experience, for there are no sweeter words than "I told you so". ;-)	[reply]


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