Draw points and lines inside a bar in bar chart - charts

Question

Who know how to draw lines and points inside a bar something like this:

Answer 1

You can draw the lines as floating bars where individual bars are specified with the syntax [min, max], same as you already do for your your other bars. Given an array of number values, the "line" data can be produced with Array.map() as follows.
data: [110, 150, 140, 100, 120].map(v => [v - 1, v + 1])
Then you need to define individual stacked xAxes for the "bar" and the "line" datasets. In order to have the original "line" values displayed in the tooltips, a toolips.callback.label function is also needed.
The points can be defined in an additional dataset of type 'scatter'.
Please have a look at below runnable code snippet.
new Chart("chart", {
type: "bar",
data: {
labels: ["4", "3", "2", "1", "0"],
datasets: [{
label: "Bars",
backgroundColor: "rgba(0, 255, 0, 0.2)",
data: [[20, 100], [50, 180], [60, 120], [10, 130], [70, 140]],
xAxisID: "x-axis-actual",
order: 1
},
{
label: "Lines",
backgroundColor: "rgb(0, 0, 0)",
data: [90, 150, 110, 90, 120].map(v => [v - 1, v + 1]),
xAxisID: "x-axis-target",
order: 2
},
{
label: "Points",
backgroundColor: "rgb(255, 255, 255)",
borderColor: "rgb(0, 0, 0)",
data: [80, 110, 90, 100, 120],
type: "scatter"
}
]
},
options: {
legend: {
display: false
},
tooltips: {
callbacks: {
label: (tooltipItem, data) => {
const dataset = data.datasets[tooltipItem.datasetIndex];
const v = dataset.data[tooltipItem.index];
return dataset.label + ': ' + (tooltipItem.datasetIndex == 1 ? (v[1] + v[0]) / 2 : tooltipItem.value);
}
}
},
scales: {
xAxes: [{
id: "x-axis-target",
stacked: true
},
{
display: false,
offset: true,
stacked: true,
id: "x-axis-actual",
gridLines: {
offsetGridLines: true
}
}
],
yAxes: [{
ticks: {
beginAtZero: true
}
}]
}
}
});
<script src="https://cdnjs.cloudflare.com/ajax/libs/Chart.js/2.9.3/Chart.min.js"></script>
<canvas id="chart" height="120"></canvas>