return tabulate data from brush selection with d3.js

Question

I adapt the scatterplot matrix designed by MBostock (see here) to my data, as you can see in this working fiddle : http://jsfiddle.net/UYqmP/

As you can see in this code, my data have this json form :

var d = ' [{"gtheta1":0.9747193937107533,"greduc-contagion":0.3775906327152618,"gtheta2":0.9377611038894604,"medOutTrafficReduction":3.0805087784299356,"medNumberPeopleInfected":99.87409839935529,"gpcr":1.0}]'

This json take lines of my original csv : [{line1},{line2},etc.]

Brush selection with d3.js permits us to select subset of value graphicaly, so my questions is simple, how can i retrieve lines which correspond to selected circle by user, and how can i display it into a dynamic table under the graphics ?

I create the div for table, and start to create a tabularfunction(), but i don't know how to retrieve the data back to selected circle (cannot find the good pointer in the d3 parameters), and how to call this tabularFunction()

tabulate(tab,["gpcr", "greduc-contagion","gtheta1","gtheta2","medNumberPeopleInfected", "medOutTrafficReduction"]) ;

function tabulate(data, columns) {

       //Retrieve selected lines from list of circle given by D3 ?

        var table = d3.select("#table").append("table").attr("style", "margin-left: 50px"),
            thead = table.append("thead"),
            tbody = table.append("tbody");

    // append the header row
    thead.append("tr")
            .selectAll("th")
            .data(columns)
            .enter()
            .append("th")
            .text(function(column) { return column; });

    // create a row for each object in the data
    var rows = tbody.selectAll("tr")
            .data(data)
            .enter()
            .append("tr");

    // create a cell in each row for each column
    var cells = rows.selectAll("td")
            .data(data)
            .enter()
            .append("td")
            .text(function(d) { return d.value; });

    return table;
}

For the call of this function, i try first to pass data retrieved by brushmove() into tabulate() but this is stupid, because at each movement of mouse, all row are added to older row, so i need to remove the previous table before redraw ...

function brushmove(p) {
    var e = brush.extent();
      var tab = svg.selectAll("circle").classed("hidden", function(d) {
        return e[0][0] > d[p.x] || d[p.x] > e[1][0]
                || e[0][4] > d[p.y] || d[p.y] > e[1][5];
     });

    //tabulate(tab,["gpcr", "greduc-contagion","gtheta1","gtheta2","medNumberPeopleInfected", "medOutTrafficReduction"]) ;

}

UPDATE 1 :

I post an example of selection :

Answer 1

I did a R/Shiny-based app with a (uni-directed) lnik between the user brush and the display of a table. Get the code here

Here's the idea :

function brushend() {
  if (brush.empty()){
    svg.selectAll(".greyed").classed("greyed", false);
  }
  var circleStates = d3.select('svg')
                    .select('g.cell')
                    .selectAll('circle'[0])
                    .map(function(d) {return d.className['baseVal']});
  Shiny.onInputChange("mydata", circleStates);
}

circleStates is then converted into a TRUE/FALSE vector, and is used as a dataframe filtering vector.

dfFilter <- input$mydata
displayDF <- baseData$df #data sent to d3.js
dfFilter[dfFilter==''] <- TRUE
dfFilter[dfFilter=='greyed'] <- FALSE
return(displayDF[dfFilter == TRUE,, drop=FALSE])

Answer 2

You can use test similar to circle to find whether line is inside select box:

function brushmove(p) {
    var e = brush.extent();
    var tab = svg.selectAll("circle").classed("hidden", function(d) {
      return e[0][0] > d[p.x] || d[p.x] > e[1][0]
              || e[0][3] > d[p.y] || d[p.y] > e[1][4];
    });

    var line = svg.selectAll("line").classed("selected-line", function(d) {
      // perform line test here
    })

    var selected_lines = svg.selectAll(".selected-line");

    //tabulate(tab,["gpcr", "greduc-contagion","gtheta1","gtheta2","medNumberPeopleInfected", "medOutTrafficReduction"]) ;

}