XP is just a number PerlMonks

### Comment on

 Need Help??

OK, I've added my routine to your benchmark program, wrapped in readmore tags below.

I've had to add and edit a bit of code outside the actual compared routines. The OP mentioned that the ratio of 1 to 0 entries is 1::500, which is a fact I used to come up with my approach. So the first change is the ability to set the probability of 1 bits.

Since the 1 bits are sparse, rather than making an explicit vector, I use a list of the positions of the 1 bits. In order to come up with the same results, I converted the Y vectors list format.

The biggest change outside of the comparison routine is the setup routine that transforms the xArray. The concept was to do something like this: Build an artificial set of vectors each with 1 bit--one vector per bit position. Then we compare each of these artificial vectors against the xArray set, resulting in a list of x vectors for each bit position. Then in our comparison, we aggregate the selected bins. Thus, if y has five bits in it, we add in the five partial products from the eigenset vectors. So the process of building the lists is amortized over the run of comparisons.

Having said all that, here it is. As mentioned previously, I came up with my approach when I saw that the distribution of 1s was very sparse. As the density of 1s increases, the routine gets progressively slower.

\$ perl 1067357_mcm.pl -I=1 -N=100 -W=4000 -P=.05 <<< snipped >>> Rate array strings bits robo array 2.33e-02/s -- -98% -99% -100% strings 1.45/s 6122% -- -25% -72% bits 1.92/s 8156% 33% -- -63% robo 5.26/s 22495% 263% 174% -- \$ perl 1067357_mcm.pl -I=1 -N=100 -W=4000 -P=.5 <<< snipped >>> s/iter array robo strings bits array 60.4 -- -87% -99% -99% robo 7.75 680% -- -91% -93% strings 0.690 8659% 1023% -- -23% bits 0.530 11304% 1362% 30% --
#! perl -slw use strict; use Benchmark qw[ cmpthese ]; use Data::Dump qw[ pp ]; \$Data::Dump::WIDTH = 500; our \$I //= -1; our \$N //= 1000; our \$W //= 15_000; # OP mentions that 1 bits are sparse (1 :: 500) It doesn't make a dif +ference for straight # bit comparison techniques, but it *does* for mine. our \$P //= 0.002; our @xArrays = map[ map { rand()<\$P ? 1 : 0 } 1 .. \$W ], 1 .. \$N; our @yArrays = map[ map { rand()<\$P ? 1 : 0 } 1 .. \$W ], 1 .. \$N; our @xStrings = map{ join '', @\$_ } @xArrays; our @yStrings = map{ join '', @\$_ } @yArrays; our @xBits = map{ pack 'b*', \$_ } @xStrings; our @yBits = map{ pack 'b*', \$_ } @yStrings; # Because the bit vectors are sparse, I'm storing them as lists of bit + positions, rather # than bit vectors, so I'm converting Y my \$start = time; our @yArrays2; for my \$y (0 .. \$#yArrays) { for my \$bitcol (0 .. \$W-1) { push @{\$yArrays2[\$y]}, \$bitcol if \$yArrays[\$y][\$bitcol]; } } my \$cur = time - \$start; print "Converting yArrays format took \$cur sec.\n"; # I bin the X arrays after which I never use them again, so I'll bin t +hem directly from the # originally generated vectors. \$start = time; our @bitcols; for my \$x (0 .. \$#xArrays) { for my \$bitcol (0 .. 14_999) { push @{\$bitcols[\$bitcol]}, \$x if \$xArrays[\$x][\$bitcol]; } } \$cur = time - \$start; print "Binning xArrays took \$cur sec.\n"; cmpthese \$I, { array => q[ my %top10s; for my \$x ( 0 .. \$#xArrays ) { for my \$y ( 0 .. \$#yArrays ) { my \$count = 0; \$xArrays[\$x][\$_] == 1 && \$yArrays[\$y][\$_] == 1 and ++\$ +count for 0 .. \$#{ \$xArrays[ 0 ] }; \$top10s{"\$x:\$y"} = \$count; my \$discard = ( sort{ \$top10s{\$a} <=> \$top10s{\$b} || +\$a cmp \$b} keys %top10s )[ 0 ]; keys( %top10s ) > 10 and delete \$top10s{\$discard}; } } \$I == 1 and pp ' arrays: ', %top10s; ], strings => q[ my %top10s; for my \$x ( 0 .. \$#xStrings ) { for my \$y ( 0 .. \$#yStrings ) { my \$count = ( \$xStrings[\$x] & \$yStrings[\$y] ) =~ tr[1] +[]; \$top10s{"\$x:\$y"} = \$count; my \$discard = ( sort{ \$top10s{\$a} <=> \$top10s{\$b} || +\$a cmp \$b} keys %top10s )[ 0 ]; keys( %top10s ) > 10 and delete \$top10s{\$discard}; } } \$I == 1 and pp 'strings: ', %top10s; ], bits => q[ my %top10s; for my \$x ( 0 .. \$#xBits ) { for my \$y ( 0 .. \$#yBits ) { my \$count = unpack '%32b*', ( \$xBits[\$x] & \$yBits[\$y] +); \$top10s{"\$x:\$y"} = \$count; my \$discard = ( sort{ \$top10s{\$a} <=> \$top10s{\$b} || +\$a cmp \$b} keys %top10s )[ 0 ]; keys( %top10s ) > 10 and delete \$top10s{\$discard}; } } \$I == 1 and pp ' bits: ', %top10s; ], robo => sub { my %top10s; my \$cur_min=0; for my \$y ( 0 .. \$#yArrays2 ) { my %x; for my \$bitcol (@{\$yArrays2[\$y]}) { \$x{\$_}++ for @{\$bitcols[\$bitcol]}; } for my \$k (keys %x) { next unless \$x{\$k} >= \$cur_min; \$top10s{"\$k:\$y"} = \$x{\$k}; my \$discard = ( sort{ \$top10s{\$a} <=> \$top10s{\$b} || \$ +a cmp \$b } keys %top10s )[ 0 ]; if (keys %top10s > 10) { \$cur_min = \$top10s{\$discard}; delete \$top10s{\$discard}; } } } \$I == 1 and pp ' bits: ', %top10s; }, };

...roboticus

When your only tool is a hammer, all problems look like your thumb.

In reply to Re^6: Comparing two arrays by roboticus
in thread Comparing two arrays by baxy77bax

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post; it's "PerlMonks-approved HTML":

• Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
• Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
• Read Where should I post X? if you're not absolutely sure you're posting in the right place.
• Please read these before you post! —
• Posts may use any of the Perl Monks Approved HTML tags:
a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
• You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
 For: Use: & & < < > > [ [ ] ]
• Link using PerlMonks shortcuts! What shortcuts can I use for linking?
• See Writeup Formatting Tips and other pages linked from there for more info.

Create A New User
Chatterbox?
 [Discipulus]: good morning nuns, monks and gods!

How do I use this? | Other CB clients
Other Users?
Others pondering the Monastery: (5)
As of 2018-04-27 06:56 GMT
Sections?
Information?
Find Nodes?
Leftovers?
Voting Booth?
My travels bear the most uncanny semblance to ...

Results (97 votes). Check out past polls.

Notices?