//highlight zero line ... Maybe should not be an option and should just be in CSS?
if(highlightZero)
g.selectAll('.tick')
.filter(function(d){return!parseFloat(Math.round(d*100000)/1000000)})//this is because sometimes the 0 tick is a very small fraction, TODO: think of cleaner technique
.filter(function(d){console.log(d);return!parseFloat(Math.round(d.__data__*100000)/1000000)})//this is because sometimes the 0 tick is a very small fraction, TODO: think of cleaner technique
.classed('zero',true);
//store old scales for use in transitions on update