seems that lookahead grep is the
slightly faster solution ...
here is the test script I used:
#!/usr/bin/perl -w
# usage : ./this_script.pl < input_file > captured_benchmarks
use strict;
use Benchmark;
my @data=<>;
my (@res1,@res2,@res3);
timethese (100000000,
{ grep_and => q{
@res1 = grep /GGGGGACACCTTCTCTCTCT/ && /RH_MEa0001bG06/, @data;
},
double_grep => q{
@res2 = grep /GGGGGACACCTTCTCTCTCT/,grep /RH_MEa0001bG06/,@data;
},
lookahead_grep => q{
@res3 = grep /^(?=.*GGGGGACACCTTCTCTCTCT)(?=.*RH_MEa0001bG06)/,@da
+ta;
}
}
);
... and the results
Benchmark: timing 100000000 iterations of double_grep, grep_and, looka
+head_grep...
double_grep :
27 wallclock secs (26.98 usr + 0.00 sys = 26.98 CPU) @ 3705899.79/s (
+n=100000000)
grep_and :
24 wallclock secs (23.05 usr + 0.00 sys = 23.05 CPU) @ 4338959.52/s (
+n=100000000)
lookahead_grep :
24 wallclock secs (22.83 usr + 0.00 sys = 22.83 CPU) @ 4380585.25/s (
+n=100000000)
-
Are you posting in the right place? Check out Where do I post X? to know for sure.
-
Posts may use any of the Perl Monks Approved HTML tags. Currently these include the following:
<code> <a> <b> <big>
<blockquote> <br /> <dd>
<dl> <dt> <em> <font>
<h1> <h2> <h3> <h4>
<h5> <h6> <hr /> <i>
<li> <nbsp> <ol> <p>
<small> <strike> <strong>
<sub> <sup> <table>
<td> <th> <tr> <tt>
<u> <ul>
-
Snippets of code should be wrapped in
<code> tags not
<pre> tags. In fact, <pre>
tags should generally be avoided. If they must
be used, extreme care should be
taken to ensure that their contents do not
have long lines (<70 chars), in order to prevent
horizontal scrolling (and possible janitor
intervention).
-
Want more info? How to link
or How to display code and escape characters
are good places to start.