d3 v4 drag line chart with x and y axes

Question

I'm new to d3.js. I wanted to drag a line chart using its points. It is working fine without the x and y axes. I have used this example as reference: https://bl.ocks.org/mbostock/4342190

With the axes to the line chart the line is not plotting correcly. Please have a look into the snippet below.

Thanks in advance.

 <!DOCTYPE html> <svg width="500" height="350"></svg> <script src="https://d3js.org/d3.v4.min.js"></script> <script> var svg = d3.select("svg"), margin = {top: 20, right: 20, bottom: 30, left: 50}, width = +svg.attr("width") - margin.left - margin.right, height = +svg.attr("height") - margin.top - margin.bottom; let points = d3.range(1, 10).map(function(i) { return [i * width / 10, 50 + Math.random() * (height - 100)]; }); var x = d3.scaleLinear() .rangeRound([0, width]); var y = d3.scaleLinear() .rangeRound([height, 0]); var xAxis = d3.axisBottom(x), yAxis = d3.axisLeft(y); var line = d3.line() .x(function(d) { return x(d[0]); }) .y(function(d) { return y(d[1]); }); let drag = d3.drag() .on('start', dragstarted) .on('drag', dragged) .on('end', dragended); svg.append('rect') .attr('class', 'zoom') .attr('cursor', 'move') .attr('fill', 'none') .attr('pointer-events', 'all') .attr('width', width) .attr('height', height) .attr('transform', 'translate(' + margin.left + ',' + margin.top + ')') var focus = svg.append("g") .attr("transform", "translate(" + margin.left + "," + margin.top + ")"); x.domain(d3.extent(points, function(d) { return d[0]; })); y.domain(d3.extent(points, function(d) { return d[1]; })); focus.append("path") .datum(points) .attr("fill", "none") .attr("stroke", "steelblue") .attr("stroke-linejoin", "round") .attr("stroke-linecap", "round") .attr("stroke-width", 1.5) .attr("d", line); focus.selectAll('circle') .data(points) .enter() .append('circle') .attr('r', 5.0) .attr('cx', function(d) { return x(d[0]); }) .attr('cy', function(d) { return y(d[1]); }) .style('cursor', 'pointer') .style('fill', 'steelblue'); focus.selectAll('circle') .call(drag); focus.append('g') .attr('class', 'axis axis--x') .attr('transform', 'translate(0,' + height + ')') .call(xAxis); focus.append('g') .attr('class', 'axis axis--y') .call(yAxis); function dragstarted(d) { d3.select(this).raise().classed('active', true); } function dragged(d) { d3.select(this) .attr('cx', d[0] = d3.event.x) .attr('cy', d[1] = d3.event.y) focus.select('path').attr('d', line); } function dragended(d) { d3.select(this).classed('active', false); } </script>

Answer 1

d3.event is holding pixel positions, but your plot is driven by user-space coordinates. So, you need to convert those pixel positions to user-space. You can use your scales invert method to do so.

function dragged(d) {
    d[0] = x.invert(d3.event.x); // convert to user-space
    d[1] = y.invert(d3.event.y);
    d3.select(this)
        .attr('cx', x(d[0])) // back to pixels
        .attr('cy', y(d[1]))
    focus.select('path').attr('d', line); //line does pixel conversion too
}

Running code:

 <!DOCTYPE html> <svg width="500" height="350"></svg> <script src="https://d3js.org/d3.v4.min.js"></script> <script> var svg = d3.select("svg"), margin = {top: 20, right: 20, bottom: 30, left: 50}, width = +svg.attr("width") - margin.left - margin.right, height = +svg.attr("height") - margin.top - margin.bottom; let points = d3.range(1, 10).map(function(i) { return [i * width / 10, 50 + Math.random() * (height - 100)]; }); var x = d3.scaleLinear() .rangeRound([0, width]); var y = d3.scaleLinear() .rangeRound([height, 0]); var xAxis = d3.axisBottom(x), yAxis = d3.axisLeft(y); var line = d3.line() .x(function(d) { return x(d[0]); }) .y(function(d) { return y(d[1]); }); let drag = d3.drag() .on('start', dragstarted) .on('drag', dragged) .on('end', dragended); svg.append('rect') .attr('class', 'zoom') .attr('cursor', 'move') .attr('fill', 'none') .attr('pointer-events', 'all') .attr('width', width) .attr('height', height) .attr('transform', 'translate(' + margin.left + ',' + margin.top + ')') var focus = svg.append("g") .attr("transform", "translate(" + margin.left + "," + margin.top + ")"); x.domain(d3.extent(points, function(d) { return d[0]; })); y.domain(d3.extent(points, function(d) { return d[1]; })); focus.append("path") .datum(points) .attr("fill", "none") .attr("stroke", "steelblue") .attr("stroke-linejoin", "round") .attr("stroke-linecap", "round") .attr("stroke-width", 1.5) .attr("d", line); focus.selectAll('circle') .data(points) .enter() .append('circle') .attr('r', 5.0) .attr('cx', function(d) { return x(d[0]); }) .attr('cy', function(d) { return y(d[1]); }) .style('cursor', 'pointer') .style('fill', 'steelblue'); focus.selectAll('circle') .call(drag); focus.append('g') .attr('class', 'axis axis--x') .attr('transform', 'translate(0,' + height + ')') .call(xAxis); focus.append('g') .attr('class', 'axis axis--y') .call(yAxis); function dragstarted(d) { d3.select(this).raise().classed('active', true); } function dragged(d) { d[0] = x.invert(d3.event.x); d[1] = y.invert(d3.event.y); d3.select(this) .attr('cx', x(d[0])) .attr('cy', y(d[1])) focus.select('path').attr('d', line); } function dragended(d) { d3.select(this).classed('active', false); } </script>

d3 v4 drag line chart with x and y axes

Question

1 answers

solution1
7 ACCPTED 2017-03-10 16:30:57

d3 v4 drag line chart with x and y axes

Question

1 answers

solution1 7 ACCPTED 2017-03-10 16:30:57

solution1
7 ACCPTED 2017-03-10 16:30:57