Error in lattice::latticeParseFormula(x, data = data) : model must be a formula object

Question

I tried to use rChart's rNVD3 package's discrete bar plot instead of the same old ggplot2. But it's requiring some formula argument as a first argument. I've not used lattice package and I don't know how to create one.

Here's my data frame:

   df <- data.frame(
      Pupil = factor(c("Richy","Shyam","Nithin"), levels=c("Richy","Shyam","Nithin")), 
      Scores = c(75,93,62)
      )

Code I used to render the plot:

  require(rNVD3)
    bar1 <- nvd3Plot(x = "Pupil", y = "Scores", data = df, type = "discreteBarChart", width = 600)
    bar1$printChart("chart1")

This is what the error is:

Error in lattice::latticeParseFormula(x, data = data) : model must be a formula object

When I tried to rectify the error:

 bar1<-nvd3Plot(Scores ~ Pupil, data = df, type = "discreteBarChart", width = 600)
    bar1$printChart("chart1")

It just showed the .js code but not the barchart.

<div id='chart1' class='nvd3Plot'></div>
    <script type='text/javascript'>
        drawchart1()
        function drawchart1(){  
          var opts = {"id":"chart1","yAxis":[],"x":"Pupil","y":"Scores","type":"discreteBarChart","width":600,"height":400},
            data = [{"Pupil":"Richy","Scores":75},{"Pupil":"Shyam","Scores":93},{"Pupil":"Nithin","Scores":62}]

          var data = d3.nest()
            .key(function(d){
              return opts.group === undefined ? 'main' : d[opts.group]
            })
            .entries(data)

          nv.addGraph(function() {
            var chart = nv.models[opts.type]()
              .x(function(d) { return d[opts.x] })
              .y(function(d) { return d[opts.y] })
              .width(opts.width)
              .height(opts.height)

           d3.select("#" + opts.id)
            .append('svg')
            .datum(data)
            .transition().duration(500)
            .call(chart);

           nv.utils.windowResize(chart.update);
           return chart;
          });
    };
</script>

Answer 1

rCharts can be a little confusing sometimes due to its use of reference classes. You are very close. First install rCharts. Then, instead of nvd3Plot, use nPlot as shown below. Also, you might be interested in htmlwidgets.

library(rCharts)

df <- data.frame(
  Pupil = factor(c("Richy","Shyam","Nithin"), levels=c("Richy","Shyam","Nithin")), 
  Scores = c(75,93,62)
)

# without formula interface
nPlot(
  x = "Pupil", y = "Scores", data = df,
  type = "discreteBarChart", width = 600
)

# with formula interface
nPlot(Scores~Pupil, data = df, type = "discreteBarChart", width = 600)