Add vertical line to line chart in rChart NVD3 (nPlot) - r

Question

I would like to add several vertical lines indicating particular events in a line chart created with nPlot. Any suggestions?
library(reshape2)
library(ggplot2)
library(rCharts)
ecm <- reshape2::melt(economics[,c('date', 'uempmed', 'psavert')], id = 'date')
p7 <- nPlot(value ~ date, group = 'variable', data = ecm, type = 'lineWithFocusChart')
Final goal: add vertical lines with labels at 'date' = '1967-11-30', '2001-11-30', '1968-01-31', etc.

Answer 1

Ok, so this should answer the question. I think you will notice that this is generally considered well beyond the skill level of an average R user. Eventually, it would be nice to write a custom chart to handle this behavior well and make easy and available to the general R user. I would like to generalize both the dashed and the vertical lines to handle in R. Here is the rCharts viewer demo and the live code example.
library(reshape2)
library(ggplot2)
library(rCharts)
ecm <- reshape2::melt(economics[,c('date', 'uempmed', 'psavert')], id = 'date')
p7 <- nPlot(value ~ date, group = 'variable', data = ecm, type = 'lineWithFocusChart')
#let's add this to make date handling easier
p7$xAxis( tickFormat="#!function(d) {return d3.time.format('%b %Y')(new Date( d * 86400000 ));}!#" )
#grab template from
#https://github.com/ramnathv/rCharts/blob/master/inst/libraries/nvd3/layouts/chart.html
#modify to add callback on graph render
p7$setTemplate(script = sprintf("
<script type='text/javascript'>
$(document).ready(function(){
draw{{chartId}}( );
});
function draw{{chartId}}( ){
var opts = {{{ opts }}};
var data = {{{ data }}};
if(!(opts.type==='pieChart' || opts.type==='sparklinePlus' || opts.type==='bulletChart')) {
var data = d3.nest()
.key(function(d){
//return opts.group === undefined ? 'main' : d[opts.group]
//instead of main would think a better default is opts.x
return opts.group === undefined ? opts.y : d[opts.group];
})
.entries(data);
}
if (opts.disabled != undefined){
data.map(function(d, i){
d.disabled = opts.disabled[i]
})
}
nv.addGraph(function() {
chart = nv.models[opts.type]()
.width(opts.width)
.height(opts.height)
if (opts.type != 'bulletChart'){
chart
.x(function(d) { return d[opts.x] })
.y(function(d) { return d[opts.y] })
}
{{{ chart }}}
{{{ xAxis }}}
{{{ x2Axis }}}
{{{ yAxis }}}
d3.select('#' + opts.id)
.append('svg')
.datum(data)
.transition().duration(500)
.call(chart);
chart.dispatch.brush.on('brushstart',function(){ drawVerticalLines( opts ) });
chart.dispatch.brush.on(
'brushend',
function(){ window.setTimeout(
function() {drawVerticalLines( opts )},
250
)}
);
nv.utils.windowResize(chart.update);
return chart;
},%s);
};
%s
</script>
"
,
#here is where you can type your vertical line/label function
"function() { drawVerticalLines( opts ) }"
,
#add the afterScript here if using with shiny
"
function drawVerticalLines( opts ){
if (!(d3.select('#' + opts.id + ' .nvd3 .nv-focus .nv-linesWrap').select('.vertical-lines')[0][0])) {
d3.select('#' + opts.id + ' .nvd3 .nv-focus .nv-linesWrap').append('g')
.attr('class', 'vertical-lines')
}
vertLines = d3.select('#' + opts.id + ' .nvd3 .nv-focus .nv-linesWrap').select('.vertical-lines').selectAll('.vertical-line')
.data(
[
{ 'date' : new Date('1967-11-30'),
'label' : 'something to highlight 1967'
} ,
{ 'date' : new Date('2001-11-30'),
'label' : 'something to highlight 2001'
}
] )
var vertG = vertLines.enter()
.append('g')
.attr('class', 'vertical-line')
vertG.append('svg:line')
vertG.append('text')
vertLines.exit().remove()
vertLines.selectAll('line')
.attr('x1', function(d){
return chart.xAxis.scale()(d.date/60/60/24/1000)
})
.attr('x2', function(d){ return chart.xAxis.scale()(d.date/60/60/24/1000) })
.attr('y1', chart.yAxis.scale().range()[0] )
.attr('y2', chart.yAxis.scale().range()[1] )
.style('stroke', 'red')
vertLines.selectAll('text')
.text( function(d) { return d.label })
.attr('dy', '1em')
//x placement ; change dy above for minor adjustments but mainly
// change the d.date/60/60/24/1000
//y placement ; change 2 to where you want vertical placement
//rotate -90 but feel free to change to what you would like
.attr('transform', function(d){
return 'translate(' +
chart.xAxis.scale()(d.date/60/60/24/1000) +
',' +
chart.yAxis.scale()(2) +
') rotate(-90)'
})
//also you can style however you would like
//here is an example changing the font size
.style('font-size','80%')
}
"
))
p7
Let me know your thoughts.