Data Manipulation

<!DOCTYPE html>

d3.tsv("barley.tsv", ready);

function ready(error, data) {
	if (error) return console.warn(error);

// declare a function
	function functionName(functionVariables) {
		// foo
	};
	// anonymous functions are used often
	var anon = function (d) { return d.foo; };
	// these functions can also return an index
	var anonIndex = function (d, i) { return d.foo+i; };

// use .map to extract from a larger data set
	var yields = data.map(function (d) { return d.yield; });

// use .filter to select data conditionally
	var grandRapidsData = data.filter(function (d) { return d.site == 'Grand Rapids'; });

// use .reduce to sum - (a, b) is critical
	var totalYields = yields.reduce( function (a,b) {
		return a + b;
	});

// use .sort to order data = (a,b) is critical
	data.sort(function (a,b) { return a.yield - b.yield; });

// map and sort together to dedupe
	var allVarieties = data.map( function (d) { return d.variety; });
	var allVarietiesDeduped = d3.set(allVarieties).values();

// min, max, extent (extent returns array with two values)
	var yieldsMin = d3.min(yields);
	var yieldsMax = d3.max(yields);
	var yieldsExtent = (d3.extent(data, function (d) { return d.yield; }));

// rounding
	var rounded = Math.round(23.2);
	var roundedDecimals = (23.42422).toFixed(2);

// reduce w. a ternary operator
	var sumYieldsOver50 = yields.reduce(function (a, b) {
		return (a > 50) ? a + b : b;
	});

data.forEach( function(d) {
		// .split, returns array of characters split by character
		d.split = d.yield.split(".");
		// .replace
		d.replace = d.yield.replace(".", ",");
		// trim whitespace
		d.trim = d.site.replace(/\d/g,'').trim();
		// substring selection
		var str = d.site;
		var strSubstring = str.substring(0, str.length);
	});

// date
	var s = [0,2];
	var date = new Date(s[0],(s[1]-1));
	// month index is 0 based (jan is 0, feb is 1)
	// day is 1 based

// will add commas
	function formatNumber (num) {
			return num.toString().replace(/(\d)(?=(\d{3})+(?!\d))/g, "$1,")
		};
	function addCommas(nStr) {
		nStr += '';
		var x = nStr.split('.');
		var x1 = x[0];
		var x2 = x.length > 1 ? '.' + x[1] : '';
		var rgx = /(\d+)(\d{3})/;
		while (rgx.test(x1)) {
		    x1 = x1.replace(rgx, '$1' + ',' + '$2');
		}
		return x1 + x2;
	};

// for x in y (x can be whatever you like)
	for (yield in yields) {
		// console.log(yield);
	};
	// other for loop
	allVarietiesDeduped.forEach(function (d) {
		// console.log(d);
	});

};

</script>

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