Monkigras 2012: Networks Of Data
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How to think of your data as a graph, and apply social network analysis to understand it.
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Monkigras 2012: Networks Of Data
- 1. networks of data Matt Biddulph @mattb | matt@hackdiary.com Every data scientist has their own favourite way of representing their data. For some people it’s Excel, and they think in rows and columns. For others it’s matrices, and they use linear algreba to interrogate their data. For me, it’s graphs.
- 2. We’re all pretty used to the idea that you can model human relationships in a social graph.
- 3. “Social network analysis views social relationships in terms of network theory consisting of nodes and ties. Nodes are the individual actors within the networks, and ties are the relationships between the actors.” There’s a pretty deep area of mathematical study called Social Network Analysis that goes back at least 20 years. It tries to create insight by analysing the structure of social networks, and usually doesn’t incorporate any elements of culture or sociology in doing so.
- 4. Centrality measures It led to the creation of techniques like centrality measures, that try to find the nodes that are most central to the network. These might be the kind of people on Twitter who have the highest chance of being retweeted.
- 5. Community detection There are also community detection algorithms that try to find the most tightly-knit subgraphs and cluster those nodes together. If you ran this over the network of people I follow on Twitter, it might be able to pick out my work colleagues or the people I socialise with face-to-face.
- 6. People you may know Sites like LinkedIn build almost-telepathic “people you may know” features by walking around the graph starting at your node and looking for people that show up a lot in your neighbourhood that you haven’t connected with yet.
- 7. To demonstrate what these techniques can do, I downloaded some data from Github’s API. I wanted to identify and map London’s most-connected developers.
- 8. acastro si mikewest lawrencec guioconnor spjwebster muffinresearch osde8info tyru dannyamey IanPouncey dennyhalim ejeliot kulor dorward cyrildoussin cheeaun marcusramberg andyhd isofarro aphillipo pierslowe acme jason23z kraih nefarioustim carlo sh1mmer cdent melo minty dann BenJam SteveMarshall yncyrydybyl gfx FND fhelmberger rjray barbie sartak rozza thrudigital NeilCrosbyginader nothingmuch tcaine perigrin bricas arcanez petemounce bingos gugod themattharris tomyan philhawksworth davorg rafl bobtfish bradleywright richardc richardhodgson norm phae salfield greut simonmaddox rjw1 stig ashb psd deanwilson tmtmtmtm drewm gillesruppert miyagawa BenWard cbetta tommorris natbat garethr jjl dwhittle dhilton mojodna thesmith sammyt evilstreak pjbarry voodoochild AndrewDisley willi iamdanw matth c9s andybeeching alfredwesterveld georgebrock simonw riklomas samsoir threebytesfull mikesten richardkeen jtweed Rodreegez dsingleton skarab molily danieljohnmorris dstrelau mattb ask webiest atl abecciu lingrch rondevera philnash bruntonspall sriprasanna Jonty Allinthedata fidothe whomwah superfeedr dvydra tonytw1 jensy cc bbcpete gklopper monkchips straup rux russss kenlim tackley steppenwells memespring vancaem bob-p kurtjx jaygooby metade james filipeamoreira chrismear hungryblank the-experimenters jwheare hubgit jystewart jonocole camelpunch evangineer fredrikmollerstrand craigw baseonmars harry-m pkqk jberkel dougma eartle thommay otfrom tonyg stever mokele Roelven danski kanzure braindeaf thmghtd andrew charlenopires julians blaine e1i45 muesli tims tobypadilla edouard rmetzler holizz joshbuddy nogeek cwninja rarepleasures hdurer matagus bileckme aubergene mxcl esneko tim ntoll mcroydon liquid tomtaylor haifeng snowblink georgepalmer eightbitraptor threedaymonk micrypt deepak brett pusewicz zachinglis digdog zaczheng crowbot thechrisoshow twoism-dev monadic jcoglan lrug professionalnerd colin danwrong techbelly ja maccman rlivsey floehopper nevali melito elliottcable lifo chris-d-adams libin flunder andrewmcdonough natematias svetlyak40wt Floppy dwo smtlaissezfaire tonylpurzelrakete ejdraper bumi lazyatom danlucraft jasoncale kalv stonegao nikolay matthewford robmckinnon reddavis bru chrisroos topfunky tomafro grillpanda newbamboo jibes21 stinie timcowlishaw baob ebrett matclayton benpickles felixcohen tomdyson timd alexstubbs cv wakatara gerhard Marak geoffgarside jaikoo BenHall olly jaigouk pablete This diagram, created in 2009, has several dimensions. Each node is a London developer with a github account. Lines show follower relationships. Nodes are sized according to number of followers, and coloured according to network centrality (red for most-central). The layout shows community structure - for example the top-left cluster is mostly Perl developers.
- 9. carlo rozza SteveMarshall FND NeilCrosbyginader themattharris tomyan philhawks radleywright richardhodgson norm phae greut simonmaddox psd drewm gillesruppert BenWard cbetta tommorris natbat garethr dwhittle dhilton mojodna the myt evilstreak pjbarry voodoochild AndrewDisley willi iamdanw andybeeching sterveld georgebrock simonw samsoir rik mikesten richardkee dsingletonskarab molily danieljohn mattb webiest atl sanna fidothe Jonty Allinthedata russss jensy superfeed memespring rux straup jaygooby monkchips vancae jonocole jwheare james filipeamore chrismear hubgit jystewart
- 10. Let’s go beyond purely social data. James Governor suggested I explore the connection between music taste and choice of programming language. I wrote a script to correlate last.fm usernames with github usernames and created a graph structure linking the music genre taste of each developer to the languages their github projects are implemented in.
- 11. This diagram is just a small sample amongst the people I follow on Github and last.fm - not enough to provide a statistically-significant judgement.
- 12. in this small sample we can see that my Ruby-coding friends tend towards sing-songwriter acoustic folk, and the Javascript coders are all about rock and indie.
- 13. This is a great book that goes into these techniques in depth. However it’s useful for any networked data, not just social networks. And it’s useful to anyone, not just startups.
- 14. This is a great book that goes into these techniques in depth. However it’s useful for any networked data, not just social networks. And it’s useful to anyone, not just startups.
- 15. This is a great book that goes into these techniques in depth. However it’s useful for any networked data, not just social networks. And it’s useful to anyone, not just startups.
- 16. So let’s take a step back and think about what other kinds of graph we could form, from what kinds of data.
- 17. I used to work in location apps at Nokia, and so I naturally think of places. Wouldn’t it be interesting to study the connections between cities instead of people? For example, people probably fly more often between NYC and LA than they do between NYC and New Jersey. We could re-draw the map based on closeness in the travel network.
- 18. In 2011 I turned to the Hadoop cluster at Nokia and took a sample of several weeks of logs from our routing servers. These are used every time someone uses our maps application to request a driving route from one place to another. Every time someone drove from A to B, I made an edge in a “place graph” from A to B.
- 19. I ran the data through Gephi and asked it to cluster it based on the strength of connections between towns. The result is a not-quite-geographic new map of the world, where two cities are close to each other if people often drive between them.
- 20. UK China Korea, Japan, etc Spain Most of Europe India Pakistan Finland Russia As you’d expect, the UK is an island and so people don’t drive in and out of it very often. Spain and Portugal are not islands, but they appear separate because they’re attached to the rest of Europe by a very narrow neck of land. So people are much more likely to fly than drive out of Spain.
- 21. Times Square = Piccadilly Circus New York London What kind of questions can this data answer? Say I’m coming to London for the first time and I’m familiar with New York. I could ask a friend what the equivalent of Times Square is in London. If they know both towns, they’d probably tell me that Times Square is the Piccadilly Circus of New York.
- 22. What is the Holborn of Amsterdam? ... the De Pijp of New York? ... the Williamsburg of London? But if we delve into the place graph, we could answer much more interesting questions, and create a “neighbourhood isomorphism” from city to city. People who like the Mission in SF and Shoreditch in London could find out that Williamsberg is probably the best place for them to stay in New York.
- 23. the Place Graph is just like the Social Graph This is just one example of viewing data as a graph and then using Social Graph analytics on it. There are many more possible - the link structure of Wikipedia, the co-occurrence of topics in a newspaper, the implicit social network of @replies on Twitter, etc.
- 24. Thanks! Matt Biddulph @mattb | matt@hackdiary.com