Common birthdays


This visu­al­isa­tion shows the pop­ular­ity of birth­days in the US between 1973 – 1999. The dark­ness of the col­our shows the rank of how pop­ular that birth­day is. Dark col­ours are more pop­ular (i.e. bet­ter ranked) birth­days.

  • Most people are born in August & September (and there­fore were con­ceived around November & December, dur­ing the hol­i­days, per­haps?)
  • However, very few people are ac­tu­ally born dur­ing hol­i­days – New year, Independence day, Halloween, Thanksgiving and Christmas. (People don’t like to spoil their hol­i­days?)
  • Few people are born on the 1st of April. (You don’t want your kid born on Fool’s Day)
  • Few people are born on the 13th of any month. (Unlucky?)
  • Plenty are born on Valentine’s Day and St Patrick’s day

We tried to see what this looked like in India.

Based on school re­gis­tra­tion data for ~700,000 stu­dents born between 1992 – 1995, here’s what it looks like. (Click for a lar­ger ver­sion.)


This shows a num­ber of bizar­re pat­terns:

  • Almost everyone’s born between May and June – just be­fore the school opens.
  • Almost no one is born in August – af­ter school opens.
  • An un­usu­al num­ber of people have round-numbered days as birth­days – 5th, 10th, 15th, 20th, 25, and 30th. (This round-numbered pat­tern was also seen when we ana­lysed util­ity fraud).
  • January 1st is fairly pop­ular. Other than that, none of the hol­i­days seem to have an ef­fect.

In fact, these res­ults are so strik­ing that we are temp­ted to be­lieve that the pop­ularly ac­cep­ted proof for a person’s age – their Class 10 cer­ti­fic­ate – gen­er­ally bears a con­veni­ent fic­tion cre­ated for the pur­poses of school ad­mis­sion sev­er­al years ago.

The Social Network of Coders

Every prob­lem faces the prob­lem of find­ing smart, mo­tiv­ated people. Joel Spolsky of­fers this ad­vice for find­ing great de­velopers:

Think about where the people you want to hire are hanging out… Go to their con­fer­ences where you’ll find early ad­op­ters who are curi­ous about new things and al­ways in­ter­ested in im­prov­ing.

These days, the smart folks hang out at Github. (Github is like Facebook for coders. Coders can fol­low each oth­er, and in­stead of up­load­ing pho­tos, they up­load code.)

Last year, Matt Biddulph pub­lished a piece on Algorithmic re­cruit­ment with Github, and plot­ted the so­cial net­work of coders on Github in spe­cific cit­ies: San Francisco and London in par­tic­u­lar. People have ex­ten­ded this ef­fort to oth­er cit­ies, but none in India.

At Gramener, we took a look at the Github fol­low­er net­work in vari­ous cit­ies in India. The im­ages be­low show the so­cial net­work of Github users at Bangalore and Chennai – the Indian cit­ies with the most users on Github.


Firstly, Bangalore, with 1460 users, clearly has more coders than Chennai (658). But what’s also in­ter­est­ing is the re­l­at­ively large net­worked cluster in Bangalore. This is some­thing that’s lack­ing in most oth­er cit­ies, as you can see be­low.


These cit­ies tend to have smal­ler, dis­par­ate clusters. Whereas, in Bangalore, if you know some of the top Github users, you can eas­ily hop from per­son to per­son and cov­er most of the pop­ular users on Github. You can also guess that Hyderabad, Mumbai and Delhi (es­pe­cially) are a bit less “so­ci­able” and tend to form is­lands, when com­pared to Chennai or Pune.

In a way, this is re­flec­ted in the city’s so­cial in­ter­ac­tion as well. It’s a whole lot easi­er to meet a group of de­velopers in Bangalore than it is in al­most any oth­er city in India.

To make your life easi­er, we’ve cre­ated a tool that lets you ex­plore this so­cial net­work.


Each coder is shown as a circle. The size of the circle in­creases with the num­ber of fol­low­ers. The col­our of the circle changes based on their primary pro­gram­ming lan­guage. The la­bels in­dic­ate their Github user ID, the num­ber of fol­low­ers and their main pro­gram­ming lan­guage. Lines in­dic­ate that a user is fol­low­ing an­other. You can move each circle around to get a bet­ter view, and click on the circle to open their Github page.

This graph is called a force-directed lay­out. They are an ex­cel­lent way of ex­plor­ing and visu­al­ising small-scale net­works in­ter­act­ively, since it lets you com­pare the struc­ture of dif­fer­ent net­works, and also drill deep in­to every node in a net­work.

Visit to see the tool in ac­tion.

Musical sunbursts

We of­ten won­der what songs would look like. Here’s our take on what Bobby McFerrin’s Don’t Worry Be Happy looks like.


This pic­ture is a spec­tro­gram of the song. It starts at the 12 o’clock po­s­i­tion, and moves clock­wise, end­ing at about 4:00 minutes. The in­tens­ity of col­our in­dic­ates the volume at dif­fer­ent fre­quen­cies – blue for high volume, red for me­di­um, yel­low for low and white for zero. The out­er ra­di­us rep­res­ents the lower fre­quen­cies and the in­ner ra­di­us the higher fre­quen­cies.

This sort of pic­ture al­most gives you a “fin­ger­print” of the song, and a feel for the kinds of ups-and-downs. For ex­ample, if you look at Bryan Adam’s Everything I Do, you can clearly see the light be­gin­ning, the some­what stronger middle; then a pause be­fore the 3:00 mark, strong again, and then fad­ing out.

Bryan Adams.Everything I Do (I Do It For You).mp3

For your amuse­ment, here are what a few more songs would look like – a mix of Bollywood, old and new.