Peterson Peterson - 9 days ago 9
Javascript Question

D3 - adding grid to simple line chart

In the following simple line chart, I want to add grid to x and y axis. Can someone help me in that?

SNIPPET:

<html>

<head>

<script src="https://cdnjs.cloudflare.com/ajax/libs/angular.js/1.4.12/angular.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.1.1/jquery.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/d3/4.3.0/d3.min.js"></script>

</head>

<body ng-app="myApp" ng-controller="myCtrl">

<svg></svg>

<script>

//module declaration
var app = angular.module('myApp',[]);

//Controller declaration
app.controller('myCtrl',function($scope){

$scope.svgWidth = 800;//svg Width
$scope.svgHeight = 500;//svg Height

//Data in proper format
var data = [
{"letter": "A","frequency": "5.01"},
{"letter": "B","frequency": "7.80"},
{"letter": "C","frequency": "15.35"},
{"letter": "D","frequency": "22.70"},
{"letter": "E","frequency": "34.25"},
{"letter": "F","frequency": "10.21"},
{"letter": "G","frequency": "7.68"},
];

//removing prior svg elements ie clean up svg
d3.select('svg').selectAll("*").remove();

//resetting svg height and width in current svg
d3.select("svg").attr("width", $scope.svgWidth).attr("height", $scope.svgHeight);

//Setting up of our svg with proper calculations
var svg = d3.select("svg");
var margin = {top: 20, right: 20, bottom: 30, left: 40};
var width = svg.attr("width") - margin.left - margin.right;
var height = svg.attr("height") - margin.top - margin.bottom;

//Plotting our base area in svg in which chart will be shown
var g = svg.append("g").attr("transform", "translate(" + margin.left + "," + margin.top + ")");

//X and Y scaling
var x = d3.scaleBand().rangeRound([0, width]).padding(0.4);
var y = d3.scaleLinear().rangeRound([height, 0]);

x.domain(data.map(function(d) { return d.letter; }));
y.domain([0, d3.max(data, function(d) { return +d.frequency; })]);

//Final Plotting

//for x axis
g.append("g")
.call(d3.axisBottom(x))
.attr("transform", "translate(0," + height + ")");

//for y axis
g.append("g")
.call(d3.axisLeft(y))
.append("text").attr("transform", "rotate(-90)").attr("text-anchor", "end");

//the line function for path
var lineFunction = d3.line()
.x(function(d) {return x(d.letter); })
.y(function(d) { return y(d.frequency); })
.curve(d3.curveLinear);

//defining the lines
var path = g.append("path");

//plotting lines
path
.attr("d", lineFunction(data))
.attr("stroke", "blue")
.attr("stroke-width", 2)
.attr("fill", "none");

});

</script>

</body>

</html>


RESULT:

enter image description here

Please, help me in finding how to add grids to the chart on both x and y axis.

Answer

First, set a class for both your axes:

//for x axis 
g.append("g")
     .attr("class", "xAxis")
     .call(d3.axisBottom(x))
     .attr("transform", "translate(0," + height + ")");

 //for y axis 
 g.append("g")
     .attr("class", "yAxis")
     .call(d3.axisLeft(y))
     .append("text").attr("transform", "rotate(-90)").attr("text-anchor", "end");

And then, using these classes, append the lines:

d3.selectAll("g.yAxis g.tick")
    .append("line")
    .attr("class", "gridline")
    .attr("x1", 0)
    .attr("y1", 0)
    .attr("x2", width)
    .attr("y2", 0);

d3.selectAll("g.xAxis g.tick")
    .append("line")
    .attr("class", "gridline")
    .attr("x1", 0)
    .attr("y1", -height)
    .attr("x2", 0)
    .attr("y2", 0);

Here is a demo:

//Data in proper format 
            var data = [
                  {"letter": "A","frequency": "5.01"},
                  {"letter": "B","frequency": "7.80"},
                  {"letter": "C","frequency": "15.35"},
                  {"letter": "D","frequency": "22.70"},
                  {"letter": "E","frequency": "34.25"},
                  {"letter": "F","frequency": "10.21"},
                  {"letter": "G","frequency": "7.68"},
            ];
						
						var width = 500, height = 300;

                //removing prior svg elements ie clean up svg 
                d3.select('svg').selectAll("*").remove();

                //resetting svg height and width in current svg 
                d3.select("svg").attr("width", width).attr("height", height);

                //Setting up of our svg with proper calculations 
                var svg = d3.select("svg");
                var margin = {top: 20, right: 20, bottom: 30, left: 40};
                var width = svg.attr("width") - margin.left - margin.right;
                var height = svg.attr("height") - margin.top - margin.bottom;

                //Plotting our base area in svg in which chart will be shown 
                var g = svg.append("g").attr("transform", "translate(" + margin.left + "," + margin.top + ")");

                //X and Y scaling 
                var x = d3.scaleBand().rangeRound([0, width]).padding(0.4);
                var y = d3.scaleLinear().rangeRound([height, 0]);

                x.domain(data.map(function(d) { return d.letter; }));
                y.domain([0, d3.max(data, function(d) { return +d.frequency; })]);

                //Final Plotting 

                //for x axis 
                g.append("g")
								.attr("class", "xAxis")
                    .call(d3.axisBottom(x))
                    .attr("transform", "translate(0," + height + ")");

                //for y axis 
                g.append("g")
								.attr("class", "yAxis")
                    .call(d3.axisLeft(y))
                    .append("text").attr("transform", "rotate(-90)").attr("text-anchor", "end");
										
										 d3.selectAll("g.yAxis g.tick") 
        .append("line") 
            .attr("class", "gridline")
            .attr("x1", 0) 
            .attr("y1", 0)
            .attr("x2", width)
            .attr("y2", 0);
            
         d3.selectAll("g.xAxis g.tick") 
        .append("line") 
            .attr("class", "gridline")
            .attr("x1", 0) 
            .attr("y1", -height)
            .attr("x2", 0)
            .attr("y2", 0);

                //the line function for path 
                var lineFunction = d3.line()
                    .x(function(d) {return x(d.letter); })
                    .y(function(d) { return y(d.frequency); })
                    .curve(d3.curveLinear);

                //defining the lines
                var path = g.append("path");

                //plotting lines
                path
                    .attr("d", lineFunction(data))
                    .attr("stroke", "blue")
                    .attr("stroke-width", 2)
                    .attr("fill", "none");
.gridline{
stroke: black;
shape-rendering: crispEdges;
stroke-opacity: .2;
}
<script src="https://d3js.org/d3.v4.min.js"></script>
<svg></svg>

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