Draw Google diagrams from a Perl script
Painting by Data
A CPAN module passes drawing instructions in object-oriented Perl to Google Chart, which draws visually attractive diagrams.
Very few people are seen with Windows laptops at open source conferences nowadays, unless, that is, they really want to be the center of attraction as stone age cave dwellers. For a while, I had been looking around to replace my old laptop when an offering by Dell caught my eye: a cute Mini 9 Ubuntu netbook at an unbeatable price of US$ 230 (Figure 1). So I finally made the move. Leif, a guy from work, even gave the cute gadget a funny nickname, "Mini-Me," after the tiny clone of Dr. Evil in the second Austin Powers movie.
My first impression was exhilarating; aside from some weird issues with ssh and the wireless driver, which I could resolve online, it actually worked! I then went on to replace the meager 512MB RAM with 2GB from a no-name supplier for just US$ 9.95. But soon after, I got suspicious: Would the netbook now consume more power in suspend mode and prematurely discharge the battery? Being an engineer by trade, I had to investigate.
From Notes to Diagrams
First, I refitted the old memory module, suspended the computer, and read the battery status of the reanimated machine at irregular intervals in the course of the next 36 hours. Figure 2 shows my hand-written notes: a list of discharge percentages and times.
One and a half days later, I repeated this procedure with the 2GB chip reinstated. The two sets of data use irregular and different measuring intervals because of the slightly unorthodox approach. To juxtapose the data graphically, as shown in Figure 3, I first had to run the script in Listing 1 to normalize the data before running the graph-discharge script in Listing 2.
The results show that the batteries initially discharge at about the same speed with either memory chip. As the batteries approach the half-way point to exhaustion, the larger memory module causes the battery to discharge more quickly, which is not worrying, but it's nice to have the hard facts visualized in an attractive diagram.
Listing 1
data-normalize
Outsourcing the Chart
The chart wasn't drawn by a program running on my local machine, but by a computer in a cluster, courtesy of Google.
The Perl script simply creates a URL, as per Figure 4, and sends it to the Google Chart service, which returns a PNG-formatted image as a result. Google restricts you to 50,000 access attempts per day, which is fine for this example.
In a previous Perl column [2] I used the service to locate spammers on a map of the world.
Object Orientation vs. the URL Jungle
To construct the URL in Figure 4, the budding chart builder has to follow the Google Chart Developer's Guide [3] carefully and encode various rules painstakingly in hard-to-read abbreviations. To make this easier, CPAN offers the Google::Chart module, which gives you an object-oriented interface to define the chart. It builds the URL step by step with the use of easily understandable method calls.
But before I start defining the chart, I first need to consolidate the measurements.
Buy Linux Magazine
Subscribe to our Linux Newsletters
Find Linux and Open Source Jobs
Subscribe to our ADMIN Newsletters
Support Our Work
Linux Magazine content is made possible with support from readers like you. Please consider contributing when you’ve found an article to be beneficial.
News
-
Canonical Bumps LTS Support to 12 years
If you're worried that your Ubuntu LTS release won't be supported long enough to last, Canonical has a surprise for you in the form of 12 years of security coverage.
-
Fedora 40 Beta Released Soon
With the official release of Fedora 40 coming in April, it's almost time to download the beta and see what's new.
-
New Pentesting Distribution to Compete with Kali Linux
SnoopGod is now available for your testing needs
-
Juno Computers Launches Another Linux Laptop
If you're looking for a powerhouse laptop that runs Ubuntu, the Juno Computers Neptune 17 v6 should be on your radar.
-
ZorinOS 17.1 Released, Includes Improved Windows App Support
If you need or desire to run Windows applications on Linux, there's one distribution intent on making that easier for you and its new release further improves that feature.
-
Linux Market Share Surpasses 4% for the First Time
Look out Windows and macOS, Linux is on the rise and has even topped ChromeOS to become the fourth most widely used OS around the globe.
-
KDE’s Plasma 6 Officially Available
KDE’s Plasma 6.0 "Megarelease" has happened, and it's brimming with new features, polish, and performance.
-
Latest Version of Tails Unleashed
Tails 6.0 is based on Debian 12 and includes GNOME 43.
-
KDE Announces New Slimbook V with Plenty of Power and KDE’s Plasma 6
If you're a fan of KDE Plasma, you'll be thrilled to hear they've announced a new Slimbook with an AMD CPU and the latest version of KDE Plasma desktop.
-
Monthly Sponsorship Includes Early Access to elementary OS 8
If you want to get a glimpse of what's in the pipeline for elementary OS 8, just set up a monthly sponsorship to help fund its continued existence.