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Question

I have three radio buttons that change the value on the x-axis for my d3 line graph. I have successfully been able to change the scales, however not the x-axis label. Everywhere I look I just see info for the tick labels, not the axes label (in the gif "Minute").

I have successfully been able to update and thus re-scale the axes as with the code below, however cannot figure out how to change the label.

    function updateGraph(graphData, timeScale){

    yDomain = d3.extent(graphData, function(d){return Number(d.amt)});

    switch(timeScale) {
        case 'min':
            xDomain = d3.extent(graphData, function(d){return Number(d.min)});
            break;
        case 'hour':
            xDomain = d3.extent(graphData, function(d){return Number(d.hour)});
            break;
        case 'day':
            xDomain = d3.extent(graphData, function(d){return Number(d.day)});
            break;
        default: break;

    }

    //Make the scale for the graphs dynamic
    yScale.domain(yDomain);

    xScale.domain(xDomain);

    vis = d3.select('#visualisation').transition();
    //add axes with proper scale, orientation, and position 

    var line = d3.svg.line()
    .x(function(d){

        switch(timeScale) {
            case 'min':
                return xScale(d.min);
                break;
            case 'hour':
                return xScale(d.hour);
                break;
            case 'day':
                return xScale(d.day);
                break;
            default: break;

        }

    })
    .y(function(d){
        return yScale(d.amt);
    })
    .interpolate('basis');

    var xAxisLabel = function(){
        switch(timeScale) {
            case 'min':
                return 'Minute';
                break;
            case 'hour':
                return 'Hours';
                break;
            case 'day':
                return 'Day';
                break;
            default: break;

        }
    }

    vis.select('.line')
        .duration(750)
        .attr('d', line(graphData))
    vis.select('.xaxis')
        .duration(750)
        .call(xAxis);
    vis.select('.yaxis')
        .duration(750)
        .call(yAxis);
    //Tried to hardcode with 'sugar' to no avail, would eventually like to use xAxisLabel declared above.
    vis.select('.text')
        .duration(750)
        .text('sugar');
}

I set the text when I first made the graph with the following code:

 vis.append('text')
        .attr('text-anchor', 'middle')  // this makes it easy to centre the text as the transform is applied to the anchor
        .attr('transform', 'translate('+ (WIDTH/2) +','+(HEIGHT+(MARGINS.bottom/3))+')')  // centre below axis
        .text(xAxisLabel);

Answer 1

Try this: first, create a variable for your text.

var textLabel = vis.append("text")
   .attr('text-anchor', 'middle')  // this makes it easy to centre the text as the transform is applied to the anchor
    .attr('transform', 'translate('+ (WIDTH/2) +','+(HEIGHT+(MARGINS.bottom/3))+')')  // centre below axis
    .text(xAxisLabel);

And then, after updating:

textLabel.duration(750).text(xAxisLabel)

Alternatively, if the above solution don't work (because vis is a transition() selection), you can simply try this one, since you are selecting a DOM element:

vis.select('.text')[0][0]
    .duration(750)
    .textContent = (xAxisLabel);

If you still get an "is not a function" error, change vis for the original variable that you used to append the svg.

Edit: don't forget to set the class "text" to the text.

Answer 2

As suggested by Gerardo in the comments, giving the label the class 'text' upon creation was the missing link.

var xAxisLabel = vis.append('text').attr("class", "text")//the rest of the code 

I was then able to change it in my update function as so:

    vis.select('.text')
    .duration(750)
    .text(xAxisLabel);

Thank you Gerardo!