var bifurcateBy = require( '@stdlib/utils-bifurcate-by' );
var inmap = require( '@stdlib/utils-inmap' );
var ttest2 = require( '@stdlib/stats-ttest2' );
var dataset = require( '@stdlib/datasets-fivethirtyeight-ffq' );

function predicate( v ) {
    return ( v.diabetes === 1 );
}

function createAccessor( field ) {
    return accessor;

    function accessor( v ) {
        return v[ field ];
    }
}

// Retrieve the data:
var data = dataset();

// Split the data into two groups based on whether a respondent has diabetes:
var groups = bifurcateBy( data, predicate );

// For each group, extract the frequency of green salad consumption:
var mapFcn = createAccessor( 'greensaladfreq' );
var g1 = inmap( groups[ 0 ].slice(), mapFcn );
var g2 = inmap( groups[ 1 ].slice(), mapFcn );

// Perform a two-sample two-sided Student's t-test to determine if green salad consumption is different between the two groups:
var results = ttest2( g1, g2 );
console.log( results.print() );