census column name prefixer

gistfile1.js

// A user may need to view a column name in isolation, with no context
// as to its level of indent. Prefixed column names allow this:
// 
// Female
//   Car, truck or van
//     Carpooled
//       In 2-person carpool
//
// to be represented as:
//
// Female: Car, truck or van: Carpooled: In 2-person carpool

comparison.prefixColumnNames = function(columns) {
    // store prefixPieces as an object with keys/values, because not all
    // tables apply indents in a standard, orderly or predictable fashion.
    // because some tables have a first non-total column with indent > 1,
    // we need to seed this with empty slots for later concatenation.
    var prefixPieces = {'0':'', '1':'', '2':''},
        prefixName,
        indentAdd;

    _.each(columns, function(v) {
        // strip occasional end chars to prep names for concatenation
        prefixName = (v.name.slice(-1) == ':') ? v.name.slice(0, -1) : v.name;
        prefixName = (prefixName.slice(-3) == ' --') ? prefixName.slice(0, -3) : prefixName;
    
        // add name piece to proper slot,
        // allowing for weird subhead columns with null indents
        prefixPieces[v.indent || 0] = prefixName;

        // compile a prefixed name that makes sense regardless of context
        v.prefixed_name = _.values(prefixPieces).slice(0, v.indent+1).filter(function(n){return n}).join(': ');
    });
}