javascriptchart.js

Bar chart with min height and zero values - ChartJs


I have a bar chart in chartjs which displays four different values. I also want these bars to have a minimum height, so that small values are better visible. For this i used the minBarLength option. The problem is that i don't want the bars which have the value zero to be affected by this option.

Is there a way to have a minimum bar length but exclude zero values or certain values in general?

Im using chartjs version 3.7.1 with the datalabel plugin 2.0.0.

<script src="https://cdnjs.cloudflare.com/ajax/libs/Chart.js/3.7.1/chart.min.js" integrity="sha512-QSkVNOCYLtj73J4hbmVoOV6KVZuMluZlioC+trLpewV8qMjsWqlIQvkn1KGX2StWvPMdWGBqim1xlC8krl1EKQ==" crossorigin="anonymous" referrerpolicy="no-referrer"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/chartjs-plugin-datalabels/2.0.0/chartjs-plugin-datalabels.min.js" integrity="sha512-R/QOHLpV1Ggq22vfDAWYOaMd5RopHrJNMxi8/lJu8Oihwi4Ho4BRFeiMiCefn9rasajKjnx9/fTQ/xkWnkDACg==" crossorigin="anonymous" referrerpolicy="no-referrer"></script>
<canvas id=chart1 height="75"></canvas>
<script>
  let chart = document.getElementById('chart1').getContext('2d');
  var dataset = {
    "labels": ["OK", "Critical", "Warning", "Unknown"],
    "datasets": [{
      "label": "Example",
      "minBarLength": "40",
      "backgroundColor": ["rgba(58, 255, 0, 0.4)", 'rgba(255, 45, 0, 0.4)', 'rgba(255, 185, 0, 0.4)', 'rgba(161, 161, 161, 0.4)'],
      "borderColor": ["rgb(58, 255, 0)", 'rgb(255, 45, 0)', 'rgb(255, 185, 0)', 'rgb(161, 161, 161)'],
      "borderWidth": 2,
      "fill": true,
      "data": [34, 0, 1, 0],
    }]
  };
  var myChart = new Chart(chart, {
    plugins: [ChartDataLabels],
    type: 'bar',
    data: dataset,
    options: {

      indexAxis: 'x',
      scales: {
        y: {
          gridLines: {
            display: false
          },
          ticks: {
            display: false
          }
        }
      },
      plugins: {
        datalabels: {
          display: function(context) {
            return context.dataset.data[context.dataIndex] !== 0;
          },
          font: {
            size: 20,
          }
        },
        legend: {
          labels: {
            boxWidth: 0
          }
        }
      }
    }
  });
</script>


Solution

  • Is there a way to have a minimum bar length but exclude zero values or certain values in general?

    ChartJS sees 0 as an value.

    To let ChartJS know that that columns shouldn't be rendered, you should use NULL for the empty cols.

    "data": [34, NULL, 1, NULL],
    

    <script src="https://cdnjs.cloudflare.com/ajax/libs/Chart.js/3.7.1/chart.min.js" integrity="sha512-QSkVNOCYLtj73J4hbmVoOV6KVZuMluZlioC+trLpewV8qMjsWqlIQvkn1KGX2StWvPMdWGBqim1xlC8krl1EKQ==" crossorigin="anonymous" referrerpolicy="no-referrer"></script>
    <script src="https://cdnjs.cloudflare.com/ajax/libs/chartjs-plugin-datalabels/2.0.0/chartjs-plugin-datalabels.min.js" integrity="sha512-R/QOHLpV1Ggq22vfDAWYOaMd5RopHrJNMxi8/lJu8Oihwi4Ho4BRFeiMiCefn9rasajKjnx9/fTQ/xkWnkDACg==" crossorigin="anonymous" referrerpolicy="no-referrer"></script>
    <canvas id=chart1 height="75"></canvas>
    <script>
      let chart = document.getElementById('chart1').getContext('2d');
      var dataset = {
        "labels": ["OK", "Critical", "Warning", "Unknown"],
        "datasets": [{
          "label": "Example",
          "minBarLength": "40",
          "backgroundColor": ["rgba(58, 255, 0, 0.4)", 'rgba(255, 45, 0, 0.4)', 'rgba(255, 185, 0, 0.4)', 'rgba(161, 161, 161, 0.4)'],
          "borderColor": ["rgb(58, 255, 0)", 'rgb(255, 45, 0)', 'rgb(255, 185, 0)', 'rgb(161, 161, 161)'],
          "borderWidth": 2,
          "fill": true,
          "data": [34, null, 1, null],
        }]
      };
      var myChart = new Chart(chart, {
        plugins: [ChartDataLabels],
        type: 'bar',
        data: dataset,
        options: {
    
          indexAxis: 'x',
          scales: {
            y: {
              gridLines: {
                display: false
              },
              ticks: {
                display: false
              }
            }
          },
          plugins: {
            datalabels: {
              display: function(context) {
                return context.dataset.data[context.dataIndex] !== 0;
              },
              font: {
                size: 20,
              }
            },
            legend: {
              labels: {
                boxWidth: 0
              }
            }
          }
        }
      });
    </script>