Create an Animated Gif with ImageMagick

I needed to create an animated series of images to observe some change over time.
To do this I decided to use ImageMagick on my linux machine. I save all of the images in a folder named image1.png, image2.png, image3.png, ... .

Then I used the following command.

convert -verbose -delay 200 -loop 0 image*.png output.gif

This takes the files named image*.png in the order that they are listed and makes a GIF out of them with a 200 hundreths of a second delay between each frame. The -loop 0 flag makes it loop indefinitely. You can put 4 in there to loop 4 times etc.

This worked fine but the order was not correct when I got over 10 images so for now I renamed them to imageA.png and went from there.

That solved my immediate need for an animated image but I need to find a neater solution to sorting the filenames.

Small Business Server 2008 Router Port Mapping

Recently my Small Business Server 2008 machine started complaining about not being able to open the router ports. I think it happened when I ran the Fix My Network Wizard to update the expiring certificates.

At some point in the past year I must have enabled uPnP on the router interface. When the wizard detects the uPnP it tries to configure the router and since it could not it was giving me error messages.

I spent a few hours trying to find some documentation on the wizard and/or figure it out. ONe of the closest places with good info was http://sbs.seandaniel.com/2008/10/fix-my-network-wizard-in-sbs-2008.html.

In the end I just turned off uPnP and reran the wizard and the errors went away.

Firefox Out of Process Config

I have run into a problem with Firefox when viewing a pdf. The pdf would not finish downloading or take a long time and it would lock up the entire browser. I couldn't switch to another tab or do anything. For some reason this seemed to happen very often when reading academic papers found on Google Scholar.

Since 3.6.4 Firefox has had the option of having a plugin run in another process. It is part of the Electrolysis project. By default  QuickTime, Flash, and Silverlight on their own process, but you can also manually add other plugins via about:config.

I wanted to add Adobe reader to see if this would help and this is how I did it.

Open about:config

right click and create a new boolean preference

name it dom.ipc.plugins.enabled.nppdf32.dll

set the boolean value to True


Restart the browser for the settings to take effect. This setting can be reversed by changing the boolean value to False.


For other plugins you can create by adding the plugin name. Those name can be found in about:plugin.

Turn of Snap in Windows 7

I am not crazy about the Snap feature in Windows 7.
The Snap feature allows you to arrange open windows, including maximizing and resizing, just by dragging and dropping a window to different edges of the screen.

To disable it click on the start button and type snap in the start search box.
A window that looks like this will open.

Click on "Prevent Windows from being ...." and then ok.

Now you should be able to move the windows and place them where you like.

Parsing Atom Feeds with Python

One of the things that I have really come to like about Python is how easy it is to prototype some code to try an idea out. I wanted to parse some blog feeds to try out some semantic analysis algorithms.

I just imported feedparser and let 'er rip.
Here is a simple example to print out the titles of this blogs Atom feed.

import feedparser

def parseit( feedurl ):
    
    data = feedparser.parse( feedurl )

    print 'Title => ' + data['title']

    print 'There are %d entries.' % (len(data['entries']))

    for entry in data['entries']:
        print entry.title

if __name__ == "__main__":

    print 'Running'
    parseit('http://dataoracle.blogspot.com/feeds/posts/default')

Dynamic R Plotting

I needed to create a graph that contained multiple lines of data.
This is relatively easy to do in R when you know about the data like the maximum values and the number of lines.
What is not so easy is to create an R script that will dynamically create the graph without knowing anything about the data ahead of time.

It appears that the call to plot() needs to have sort of parameters to create graph.
Just calling plot.new() isn't going to give me the results that I need.
I am certain that there is a better way to do this but it works.
I just used a counter in the loop and if it is the first time through I call plot with the first line.
If it is not the first time through then the lines() method is called to add the data.

The colors are dynamically created based on the number of lines.

# required libraries
library(RMySQL)

cntr <- 1# set a counter that will represent the # of times through the loop

# connect to db using credentials in my.cnf
dbcon <- dbConnect( MySQL(), group="localnfl")

# get the years with data from the database
# returns a data frame
years <- dbGetQuery( dbcon, "SELECT DISTINCT( year) FROM nfl.bet_lines")

#define the image that will hold the graph
png("../../public_html/betline.png", width=1024, height=1024)

#create a vector to hold text for legend
legend_text <- character()

# choose enough colors (one for each year)
# returns a character vector
colors = rainbow( length(years$year) )
# iterate over each year
for( y in years$year )
{
  #create a string that will be the SQL
  # used this as a poor man's prepared statement to pass in year
  sql <- sprintf("SELECT IF( (hscore-vscore)>0 AND lineopen>0,
                         ABS(lineopen- (hscore-vscore))*1,
                         ABS(lineopen- (hscore-vscore))*-1) AS mov
                  FROM nfl.bet_lines
                  WHERE week <= 17 AND year = %d
                  ORDER BY mov asc",y )

  # run the query returns a one column data frame
  values <- dbGetQuery( dbcon, sql )

  # if this is the first time through create the plot with
  # type="n" for no actual plot ( could probably just plot the first line)
  if( cntr == 1 )
  {
    # create the plot with no axes labels( ann =FALSE )
    plot( row.names(values), values$mov, ylim=c(-50,50), type="n", ann=FALSE )
  }

  lines( values$mov, type="l", lwd="2", col=colors[cntr] )

  #add the current year numeric value to the legend text as a string
  legend_text[length(legend_text)+1] = as.character(y)

  cntr <- cntr + 1  #increment the counter
}

#create the main title, double font size(cex=2), italic is 4
title(main="Mad Title", cex.main=2, font.main=4)

# place text on top(3)
mtext( "actual > 0 and opening line > 0", 3 )

# Label the x and y axes
title(ylab="| Line - Actual |")
title(xlab="Game Number")

#create the legend
legend( "topleft", legend_text, fill=colors )

dev.off()

dbDisconnect(dbcon) 

Let me know if you have any suggestions on improving this R script.

R Convert Numbers to String

For a recent R graph I needed to pull some numbers out of a database and later use those numbers as labels in the graph legend.

The legend method takes a "character or expression vector" NOT a vector of numbers much to my dismay. So I was left with a vector of numbers that I wanted to use as a legend and the legend method would not accept them. I was unable to find a method that converted this for me a`la java ( String.valueOf() ).

Here is how I did it:

#assume a vector of numbers already exists
numbers <- c(10,20,30,40)

#create a vector to hold text for legend
legend_text <- character()

#add the current numeric value to the legend text as a string
for number in numbers
{
  legend_text[length(legend_text)+1] = as.character(number)
}

#legend_text now contains a character vector and can be passed to the legend method

Blogger Code Highlighting

I wanted to add code highlighting to the blog to make things easier to read.
After a bit of searching on easy ways to implement code highlighting on Blogger I found a few sites like Sandro's that used Google's code prettify.

I added the following lines to the head section of the blogger template.

<link href="http://google-code-prettify.googlecode.com/svn/trunk/src/prettify.css" type="text/css" rel="stylesheet" />
<script type="text/javascript" src="http://google-code-prettify.googlecode.com/svn/trunk/src/prettify.js">  </script>

Then I change body tag in your template to include onload="prettyPrint()":

>
...
<body onload='prettyPrint()'>
...

Now all you have to do when you want highlighted piece of code in your blog is to use.

<pre class="prettyprint">
... # Your code goes here
</pre>

There is another style which includes line numbers that I may try in the near future.
An example can be found here.

Content Negotiation Apache Style

Content Negotiation is a complex sounding term for what is really a simple process.

Imagine calling your doctor's office to make an appointment. You tell them what dates you prefer and they respond with the opening that best fits your preference.

The Wikipedia entry on content negotiation is kind of sparse but has links to the RFC and other information.

Apache can handle content negotiation and if the apache server is configured to allow it, you can turn on per directory Content Negotiation with an htaccess file.

Contents of .htaccess file

Options All +MultiViews

The permissions of the .htaccess file should be readable

-rw----r-- 1 owner group 24 2010-02-08 19:48 .htaccess

Apache instructions for Content Negotiation

Then you can put multiple files in the same directory with the same name.
e.g.
image.png
image.gif
image.jpeg

When a user requests the image like http://example.com/image the browser will negotiate with the server for the preferred image type.

MySql Shortcut

If you access a MySql database from a linux machine here is a tip that can save you some time. In your home directory create a file named .my.cnf. That is dot-my-dot-cnf.

Then in that file you can create multiple entries like the following:

[client]
user=username
password=%!;*;^123
host=localhost

Now when you ssh in and type mysql, the client will automatically parse and use those credentials. You can specify multiple hosts if you want like this:

[client]
user=username
password=%$**^123
host=hosta.example.com

[client]
user=usernameB
password=%B^123
host=hostb.example.com

Then the MySql client will choose the proper set depending on the host you are connecting to. This feature served me well when using R scripts. In a R script that access a database you can specify the particular client group that you want to use.

In the .my.cnf file.

[Rdata]
user=Ruser
password=password
host=localhost

Then in the R file itself you can create the connection like this:

dbcon <- dbConnect( MySQL(), group="Rdata")

Now you can move the script around or share it without worrying about revealing your password information.