Wednesday, 14 November 2012

YAUSEM (Yet Another US Election Map)

The usual US election map is a starkly simplistic collection of red and blue blobs.  This does reflect the esoteric (to a Canadian) Electoral College first-past-the-post arrangement.  But after seeing how close the actual vote counts were in most states, it seemed to me like this doesn't really reflect the actual political reality of the US.  Really it's pretty much a purely purple country.  John Nelson has a nice map that elegantly visualizes this reality at a county level (and Brian Timoney explains why it's the only map that isn't a lie).

As another attempt at map truthiness, I used JEQL to produce the following map.  It shows actual vote numbers at a state level, color themed along two dimensions:
  • The hue shows the relative proportion of Democrat VS Republican votes (using the now-canonical blue and red).  For reference, Florida is almost exactly 50-50.  This nicely shows that really the US is just varying shades of purple.
  • The saturation is proportional to the relative population of the state.  California is fully saturated, since it's the most populous state.  The the inland Western and the far Northeastern states are pretty pale, since they have fairly low populations.  This is roughly proportional to the weight of the state's Electoral College votes, although there are amusing anomalies.

I make no claim that this map represents any valid statistics - it's just a fun exercise in using JEQL to do spatial visualization.  For reference, the script is:

CSVReader t colSep: "\t" file: "us_vote_raw.txt";

t = select String.trim(col1) name,
    Val.toInt(String.keepChars(col2, "0123456789")) ecVote,
    Val.toDouble(String.keepChars(col4, "0123456789")) demvote,
    Val.toDouble(String.keepChars(col5, "0123456789")) repvote from t;

Print t;

maxVote = val(select max(demvote+repvote) from t);

ShapefileReader tus file: "us_state.shp";

tvote = select name, demvote, repvote, GEOMETRY,
        demvote / (demvote+repvote) demfrac,
        demvote+repvote totvote,        

       (demvote+repvote)/maxVote density
    from t
    join tus on == String.trim(tus.STATE_NAME);

Mem tvote;

tplot = select GEOMETRY,
    #ffffff styleStroke,
    1 styleStrokeWidth
    with {
        clr = Color.interpolate("ff0000", "0000ff", demfrac);
        h = Color.getH(clr);
        s = density;
        v = 1;
        styleFill = Color.toRGBfromHSV(h,s,v);    }   
    from tvote;

extent = BOX(-128 20, -65 50);

Plot    data: tplot
    extent: val(extent)
    width: 800
    height: 400
    background: "0000aa"
    file: "us_vote.png";

The raw data came from Wikipedia via simple cut-and-paste to a text file.

No comments: