Tag Archive for 'programming'

Web2.0-generated wallpapers

on 2008 August 13
in Soft Hacks
. Comments
blog pag background

Blog page background header

I decided to create a backround header image for my blog and Multiply page. Tons of randomly writter equations would be nice to have. The Yahoo Image search allows you to specify if you the types of pictures you want like black and white photos, image size, etc. I used the yahoo_collage.pl from Uppal’s blog and modified it to exceed the maximum images per query of 50 limit from Yahoo’s image search api. Below is the patch:

*** yahoo_collage.pl	2005-09-16 20:07:50.000000000 -0500
--- ycollage.pl	2008-08-13 13:56:45.000000000 -0500
***************
*** 1,4 ****
! #! /usr/local/bin/perl -w
  ################################################################################
  # Yahoo Image Search Collage Generator
  #
--- 1,4 ----
! #! /usr/bin/perl -w
  ################################################################################
  # Yahoo Image Search Collage Generator
  #
*************** my $count   = 50;
*** 33,38 ****
--- 33,39 ----
  my $file    = undef;
  my $width   = 50;
  my $height  = 50;
+ my $init = 0;

  GetOptions(
      'query=s'   => \$query,
*************** GetOptions(
*** 41,46 ****
--- 42,48 ----
      'width=i'   => \$width,
      'height=i'  => \$height,
      'help'      => \$help,
+     'init=i'      => \$init,
  );

  if ($help) {
*************** if ($help) {
*** 56,71 ****

  die("Must specify a query!\n") unless ($query);

! if ($count > Yahoo::Search::MaxCount('Image')) {
!     die("Yahoo! does not allow querying for more than " .
!         Yahoo::Search::MaxCount('Image') . " results at once!\n");
! }

  print STDERR "Querying Yahoo for "$query"...\n";
! my @results = Yahoo::Search->Results(
      Image => $query,
!     Count => $count,
! );

  print STDERR "Generating HTML...\n";
--- 58,86 ----

  die("Must specify a query!\n") unless ($query);

! #if ($count > Yahoo::Search::MaxCount('Image')) {
! #    die("Yahoo! does not allow querying for more than " .
! #        Yahoo::Search::MaxCount('Image') . " results at once!\n");
! #}

  print STDERR "Querying Yahoo for "$query"...\n";
! my $summary = Yahoo::Search->Query(
      Image => $query,
!     Count => "50",
! 	Start => $init,
! 	Color => "bw")->CountAvail;
! my $i;
! my @results;
! for($i = $init; $i < $count + $init; $i += 50)
! {
!     my @partial = Yahoo::Search->Results(
!         Image => $query,
! 		Start => $i,
!         Count => 50,
!         Color => "bw");
! 	push (@results, @partial);
! }
! print "Generated image $init to $i from $summary\n";

  print STDERR "Generating HTML...\n";
*************** sub generate_html {
*** 92,99 ****
      my $html_images = "";

      foreach my $image_result (@$ra_results) {
!         $html_images .= "<a href="" . $image_result->HostUrl() . ""> <img src="" .
!                         $image_result->ThumbUrl() . "" width=$width height=$height></a>";
      }

      my $html_credits = qq{Created with <a href="http://upster.blogspot.com">Siddharth Uppal</a>'s
--- 107,114 ----
      my $html_images = "";

      foreach my $image_result (@$ra_results) {
!         $html_images .= "<img src="" .
!                         $image_result->ThumbUrl() . "" border=0> ";
      }

      my $html_credits = qq{Created with <a href="http://upster.blogspot.com">Siddharth Uppal</a>'s
*************** sub generate_html {
*** 104,120 ****
      my $html_page = qq{
          <html>
          <head>
!         <title>Yahoo Image Search Collage Generator: $query</title>
          </head>
!         <body><center>
!         <font face="Trebuchet MS" color="Black" size="4"><b>$query</b></font><br>
!         <p align="center">$html_images</p>
!         <font face="Trebuchet MS" color="Black" size="2"><br><b>
!         To show off your collage, just copy and paste the text below into your blog or website!<br><br>
!         <textarea rows="25" cols="50">$html_images<br>$html_credits</textarea><br><font size="1"
!         face="Verdana" color="Gray">
!         </b><br>$html_credits
!         </center></body>
          </html>
      };

--- 119,129 ----
      my $html_page = qq{
          <html>
          <head>
!         <title>$query</title>
          </head>
!         <body style="width: 1024px;">
! 		<p align="center">$html_images</p>
!         </body>
          </html>
      };

Here are some selected of my generated collages:

latex equation

latex equation

modulator

modulator

Unix timer utility

on 2008 August 8
in Soft Hacks
. Comments
Timer microbenchmark

Timer utilities performance on C and Perl of "echo -n"

The Unix time(1) command can only give a precision of 10 milliseconds by default. But being the engineer who goes insane after precision, I made my own script to be able to get differences in terms of microseconds. My first timer utility was made in C but I got stuck with the insane exec(3) family of functions since you need to fork the process to a child for the parent process to create successful timing. Hence I used Perl with the Time::HiRes library which is a wrapper to <time.h> and <sys/time.h>. Later on, I found out that C itself has the system(3) functioin in <stdlib.h>

Performance-wise you can see that C has a much faster runtime when the program was being invoked. But you can see in the graph above that Perl has much more consistent values so its standard deviation is lower than C. When I tested both programs for my data-intensive computing experiments, I get better results with the Perl utility! Perhaps I forgot to do all the magic the system function in Perl does in my C implementation?

Here is my Perl code:

#!/usr/bin/perl

use Time::HiRes qw ( tv_interval gettimeofday );

$start = [gettimeofday];
system @ARGV;

$elapsed = tv_interval ( $start );
print $elapsed, "\n";

Here is my C implementation:

#include <stdlib.h>
#include <stdio.h>

#include <time.h>
#include <sys/time.h>

int main(int argc, char* argv[])
{
	struct timeval start, end, diff;
	gettimeofday(&start, NULL);
	char* command = malloc( sizeof(argv) );
	int i;
	sprintf(command, "%s", argv[1]);
	for( i = 2; i < argc; i++ )
	{
		sprintf(command, "%s %s", command, argv[i]);
	}
	system(command);
	gettimeofday(&end, NULL);
	timersub(&end, &start, &diff);
	printf("%d.%06d\n", diff.tv_sec, diff.tv_usec);
	return 0;
}

ACM ICPC Philippines 2007

on 2007 November 6
in Soft Hacks and Theoretical Hacks
. Comments

Since the Asia Regionals site was moved back to Singapore from Manila. Dr. Raffy Saldana, the regional contest director wants to keep the momentum of competitive programming in the Philippines. So Computing Society of the Philippines (CSP) decided to organized an ICPC-style nationwide programming contest. The event was hosted by De La Salle University-Canlubang.

icpc2007poster

A parallel event to the programming contest is a series of talks sharing best programming practices regarding ACM-stylecompetitive programming. Ateneo de Manila University’s head coach, Dr. Pablo Manalastas shared mentoring stratagies. I was invited to speak about “Best Practices in Computer Programming” together with Topher Rigor. We were both members of The Linden BoyZ who particpated in the 2006 San Antonio World Finals. Below is the slide presentation of my part of the talk:

In the first slides of my presentation, I told the audience that ICPC-style programming contests does not promote good programming practice. I reminisced how we used obscure variable names like z, zz, zzz, ___, ___, _____ . And then the rest of the talk was about how to build skills individually and as a team. The talk we delivered was very short and I tried as much as I can to stretch the program by referring to key programming contests events and how we tackled challenges. I felt very much like a retired soldier telling war stories to his grandchildren.