Hello,
How to execute a call back function after aio_write() or aio_read() in Sun Solaris 5.7?
I have filled the control block struct aiocb as follows:
aio_sigevent.sigev_signo = SIGEV
aio_sigevent.sigev_notify = SIGEV_THREAD
Then I have filled the call back function in ... (0 Replies)
Actually I got a list of file end with *.txt
I want to use the same command apply to all the *.txt
Thus I try to find out the fastest way to write those same command in a script and then want to let them run automatics.
For example:
I got the file below:
file1.txt
file2.txt
file3.txt... (4 Replies)
Hi All,
I am using splice function in for loop to delete particular element from array with one condition.
my $cnt=0;
foreach my $elem (@result)
{
if (condition){
splice(@result, $cnt, 1);}
else{
$cnt++;}
}
Now when in array, two elements comes sequentially with the... (3 Replies)
I need to detect the number of pages in a print job when it is available so I can warn users when they try to print a report much larger than they expected. Sometimes they are trying to print 1000 page reports when they thought they were getting a 10 page report.
Under linux I am scanning the... (5 Replies)
Hi, I have a file like this
SPF_HC00001|iCalcular_Monto_Minimo|--->|SPF_HC00028|pstcObtener_Monto_Minimo
SPF_HC00004|iCalcular_Incrementos|--->|SPF_HC00032|pstcObtener_Num_Incrementos
SPF_HC00005|iCalcular_Articulo_167_Reformado|--->|SPF_HC00031|pstcObtener_Por_CB_Inc... (2 Replies)
Hello Unix experts,
If I could get any explanations on why the code below doesn't work it would be great !
My input looks like that ("|" delimited):
Saaaaabbbbbccccc|ok
Sdddddfffffggggg|ok
The goal is, if $2 is "ok", to remove everything before the pattern given in the match function... (5 Replies)
hey guys, im trying to learn bourne shell atm and I'm having some issues with functions.
so heres my code:
#!/bin/bash
##functions
memory () {
free -m
}
space () {
df -h
}
ip () { (5 Replies)
Hi,
I am having script which contains many functions. Need to print each function name at the starting of the function. Like below,
functionname()
{
echo "functionname"
commands....
}
I've tried like below,
func=`grep "()" scriptname | cut -d "(" -f1`
for i in $func
do
nawk -v... (4 Replies)
Discussion started by: Sumanthsv
4 Replies
LEARN ABOUT SUSE
dbd::sqlite::cookbook
DBD::SQLite::Cookbook(3) User Contributed Perl Documentation DBD::SQLite::Cookbook(3)NAME
DBD::SQLite::Cookbook - The DBD::SQLite Cookbook
DESCRIPTION
This is the DBD::SQLite cookbook.
It is intended to provide a place to keep a variety of functions and formals for use in callback APIs in DBD::SQLite.
Variance
This is a simple aggregate function which returns a variance. It is adapted from an example implementation in pysqlite.
package variance;
sub new { bless [], shift; }
sub step {
my ( $self, $value ) = @_;
push @$self, $value;
}
sub finalize {
my $self = $_[0];
my $n = @$self;
# Variance is NULL unless there is more than one row
return undef unless $n || $n == 1;
my $mu = 0;
foreach my $v ( @$self ) {
$mu += $v;
}
$mu /= $n;
my $sigma = 0;
foreach my $v ( @$self ) {
$sigma += ($x - $mu)**2;
}
$sigma = $sigma / ($n - 1);
return $sigma;
}
# NOTE: If you use an older DBI (< 1.608),
# use $dbh->func(..., "create_aggregate") instead.
$dbh->sqlite_create_aggregate( "variance", 1, 'variance' );
The function can then be used as:
SELECT group_name, variance(score)
FROM results
GROUP BY group_name;
Variance (Memory Efficient)
A more efficient variance function, optimized for memory usage at the expense of precision:
package variance2;
my $sum = 0;
my $count = 0;
my %hash;
sub new { bless [], shift; }
sub step {
my ( $self, $value ) = @_;
# by truncating and hashing, we can comsume many more data points
$value = int($value); # change depending on need for precision
# use sprintf for arbitrary fp precision
if (defined $hash{$value}) {
$hash{$value}++;
} else {
$hash{$value} = 1;
}
$sum += $value;
$count++;
}
sub finalize {
my $self = $_[0];
# Variance is NULL unless there is more than one row
return undef unless $count > 1;
# calculate avg
my $mu = $sum / $count;
my $sigma = 0;
foreach my $h (keys %hash) {
$sigma += (($h - $mu)**2) * $hash{$h};
}
$sigma = $sigma / ($count - 1);
return $sigma;
}
The function can then be used as:
SELECT group_name, variance2(score)
FROM results
GROUP BY group_name;
Variance (Highly Scalable)
A third variable implementation, designed for arbitrarily large data sets:
package variance;
my $mu = 0;
my $count = 0;
my $S = 0
sub new { bless [], shift; }
sub step {
my ( $self, $value ) = @_;
$count++;
$delta = $value - $mu;
$mu = $mu + $delta/$count
$S = $S + $delta*($value - $mu);
}
sub finalize {
my $self = $_[0];
return $S / ($count - 1);
}
The function can then be used as:
SELECT group_name, variance3(score)
FROM results
GROUP BY group_name;
SUPPORT
Bugs should be reported via the CPAN bug tracker at
http://rt.cpan.org/NoAuth/ReportBug.html?Queue=DBD-SQLite <http://rt.cpan.org/NoAuth/ReportBug.html?Queue=DBD-SQLite>
TO DO
* Add more and varied cookbook recipes, until we have enough to turn them into a seperate CPAN distribution.
* Create a series of tests scripts that validate the cookbook recipies.
AUTHOR
Adam Kennedy <adamk@cpan.org>
COPYRIGHT
Copyright 2009 Adam Kennedy.
This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.
The full text of the license can be found in the LICENSE file included with this module.
perl v5.12.1 2010-01-08 DBD::SQLite::Cookbook(3)