Establish a minimum threshold for movements in the line graph

Question

Establish a minimum threshold for movements in the line graph

While working on implementing line charts for my data, I encountered an issue. My goal is to display daily order data over the past month. There are months where no orders are placed for a specific product, and then there are months with high order volumes.

This is what I have within the options:

scales: {
    yAxes: [{
        ticks: {
            beginAtZero: true,
            callback: function (value) { if (Number.isInteger(value)) {return value; } }
        }
    }]
}

I utilized the callback function to ensure that only integers are displayed on the y-axis. However, a new problem arises when no data is present, as it shows only one step:

https://i.sstatic.net/EFI98.png

I attempted using the max: 10 option, but this caused data to be cut off if there were more than 10 orders. I couldn't find an option like minSteps: 10 or similar. Does anyone have a solution for this?

javascript chart.js

Answer 1

Answer №1

If you want to ensure that a specific value always shows on the chart, you can create a second dataset with all values set to 10 and then hide it in the legend by making it transparent and non-hitable:

var options = {
  type: 'line',
  data: {
    labels: ["Red", "Blue", "Yellow", "Green", "Purple", "Orange"],
    datasets: [{
        label: '# of Votes',
        data: [0, 0, 0, 0, 0, 0],
        borderColor: 'blue'
      },
      {
        label: 'filler',
        data: [10, 10, 10, 10, 10, 10],
        borderWidth: 1,
        fill: false,
        pointHitRadius: 0,
        radius: 0,
        hoverRadius: 0,
        borderColor: '#00000000'
      }
    ]
  },
  options: {
    legend: {
      labels: {
        filter: (lEl) => (lEl.text !== 'filler')
      }
    },
    scales: {
      yAxes: [{
        ticks: {
          reverse: false
        }
      }]
    }
  }
}

var ctx = document.getElementById('chartJSContainer').getContext('2d');
new Chart(ctx, options);

<body>
  <canvas id="chartJSContainer" width="600" height="400"></canvas>
  <script src="https://cdnjs.cloudflare.com/ajax/libs/Chart.js/2.9.4/Chart.js"></script>
</body>

UPDATE:

To always display a specific maximum value unless the data exceeds it, consider using the suggestedMax option in your Chart.js configuration:

var options = {
  type: 'line',
  data: {
    labels: ["Red", "Blue", "Yellow", "Green", "Purple", "Orange"],
    datasets: [{
      label: '# of Votes',
      data: [0, 0, 0, 0, 0, 0],
      borderColor: 'blue'
    }]
  },
  options: {
    scales: {
      yAxes: [{
        ticks: {
          suggestedMax: 10
        }
      }]
    }
  }
}

var ctx = document.getElementById('chartJSContainer').getContext('2d');
new Chart(ctx, options);

<body>
  <canvas id="chartJSContainer" width="600" height="400></canvas>
  <script src="https://cdnjs.cloudflare.com/ajax/libs/Chart.js/2.9.4/Chart.js"></script>
</body>

Answer 2

If you want to ensure that a specific value always shows on the chart, you can create a second dataset with all values set to 10 and then hide it in the legend by making it transparent and non-hitable:

var options = {
  type: 'line',
  data: {
    labels: ["Red", "Blue", "Yellow", "Green", "Purple", "Orange"],
    datasets: [{
        label: '# of Votes',
        data: [0, 0, 0, 0, 0, 0],
        borderColor: 'blue'
      },
      {
        label: 'filler',
        data: [10, 10, 10, 10, 10, 10],
        borderWidth: 1,
        fill: false,
        pointHitRadius: 0,
        radius: 0,
        hoverRadius: 0,
        borderColor: '#00000000'
      }
    ]
  },
  options: {
    legend: {
      labels: {
        filter: (lEl) => (lEl.text !== 'filler')
      }
    },
    scales: {
      yAxes: [{
        ticks: {
          reverse: false
        }
      }]
    }
  }
}

var ctx = document.getElementById('chartJSContainer').getContext('2d');
new Chart(ctx, options);

<body>
  <canvas id="chartJSContainer" width="600" height="400"></canvas>
  <script src="https://cdnjs.cloudflare.com/ajax/libs/Chart.js/2.9.4/Chart.js"></script>
</body>

UPDATE:

To always display a specific maximum value unless the data exceeds it, consider using the suggestedMax option in your Chart.js configuration:

var options = {
  type: 'line',
  data: {
    labels: ["Red", "Blue", "Yellow", "Green", "Purple", "Orange"],
    datasets: [{
      label: '# of Votes',
      data: [0, 0, 0, 0, 0, 0],
      borderColor: 'blue'
    }]
  },
  options: {
    scales: {
      yAxes: [{
        ticks: {
          suggestedMax: 10
        }
      }]
    }
  }
}

var ctx = document.getElementById('chartJSContainer').getContext('2d');
new Chart(ctx, options);

<body>
  <canvas id="chartJSContainer" width="600" height="400></canvas>
  <script src="https://cdnjs.cloudflare.com/ajax/libs/Chart.js/2.9.4/Chart.js"></script>
</body>

Answer 3

Answer №2

Expanding on the insights shared by @LeeLenalee, I have made updates to the code using chart.js version v.3x

Therefore, my recommendation would be:

Upgrade to the latest version of chart.js v3.5.1:
in your code, ensure you include both links for
enhanced performance and added features, especially when dealing with date-based data in your scenario. (v3.x is not compatible with v2.x)
Implement the use of Time Cartesian Axis
understand the distinction between "time" (regular intervals) and "timeseries" (based on data points)
you might need to incorporate momentjs and chartjs-adapter-moment (refer to the provided code snippet) or consider using luxon as suggested by @LeeLenalee (X-axis can display daily, weekly, monthly, yearly views - moment.js streamlines the filtering process). This will be beneficial for you 😜

Please confirm if the specified environment and data structure align with your requirements (I made an educated guess about your data structure):

let yourDataJson = [{x: '2021-08-13', y: 20.2},{x: '2021-08-15', y: 16},{x: '2021-08-19', y: 9},{x: '2021-08-23', y: 35},{x: '2021-09-02', y: 2}];

let yourData = {
  datasets: [{
    label: 'Orders: Product A',
    data: yourDataJson,
    borderColor: 'rgba(0,0,255,1)',
    backgroundColor: 'rgba(0,0,255,0.5)',
    fill: true
  }
  ]
};

let yourOptions = {
  scales: {
    x: { // <-- v3.x now object "{", not array "[{" anymore
      type: 'timeseries', // <-- try "time" and "timeseries" to see difference
      time: {
        unit: 'day', // <-- set 'hour' / 'day' / 'week' / 'month' or 'year'
        displayFormats: {
          hour: 'h:mm a',
          day: 'ddd, MMM DD, YYYY',
          week: 'dddd',
          month: 'MMM'
        },
        tooltipFormat: 'dddd, MMM DD, YYYY' // <-- new in v3.x
      },
      ticks: {
        minRotation: 80, // avoiding overlapping of x-Axis ticks
        maxRotation: 90
      }
    },
    y: { // <-- v3.x now object "{", not array "[{" anymore
      ticks: {
        beginAtZero: true,
        callback: function (value) {
          if (Number.isInteger(value)) return value;
        }
      },
      suggestedMin: 0,
      // the data maximum used for determining the ticks is Math.max(dataMax, suggestedMax)
      suggestedMax: 10
    }
  }
};

const ctx = document.getElementById('chartJSContainer').getContext('2d');
const myChart = new Chart(ctx, {
  type: 'line',
  data: yourData,
  options: yourOptions
});

document.querySelector('#btnTime').addEventListener('click', () => {
  myChart.options.scales['x'].type = 'time';
  myChart.update();
});
document.querySelector('#btnTimeseries').addEventListener('click', () => {
  myChart.options.scales['x'].type = 'timeseries';
  myChart.update();
});

<!-- <script src="https://cdnjs.cloudflare.com/ajax/libs/Chart.js/2.9.4/Chart.js"></script> -->

<!-- Obtain the most recent version of Chart.js, currently at v3.5.1 -->
<script src="https://cdn.jsdelivr.net/npm/chart.js"></script>

<!-- To utilize x-Axis types 'time' or 'timeseries', additional libraries are required -->
<!-- (such as moment.js and its adapter) -->
<script src="https://cdnjs.cloudflare.com/ajax/libs/moment.js/2.29.1/moment.min.js"></script>
<script src="https://cdn.jsdelivr.net/npm/chartjs-adapter-moment"></script>

<button id='btnTime'>time</button>
<button id='btnTimeseries'>timeseries</button>

<canvas id="chartJSContainer" width="600" height="400"></canvas>

Answer 4

Expanding on the insights shared by @LeeLenalee, I have made updates to the code using chart.js version v.3x

Therefore, my recommendation would be:

Upgrade to the latest version of chart.js v3.5.1:
in your code, ensure you include both links for
enhanced performance and added features, especially when dealing with date-based data in your scenario. (v3.x is not compatible with v2.x)
Implement the use of Time Cartesian Axis
understand the distinction between "time" (regular intervals) and "timeseries" (based on data points)
you might need to incorporate momentjs and chartjs-adapter-moment (refer to the provided code snippet) or consider using luxon as suggested by @LeeLenalee (X-axis can display daily, weekly, monthly, yearly views - moment.js streamlines the filtering process). This will be beneficial for you 😜

Please confirm if the specified environment and data structure align with your requirements (I made an educated guess about your data structure):

let yourDataJson = [{x: '2021-08-13', y: 20.2},{x: '2021-08-15', y: 16},{x: '2021-08-19', y: 9},{x: '2021-08-23', y: 35},{x: '2021-09-02', y: 2}];

let yourData = {
  datasets: [{
    label: 'Orders: Product A',
    data: yourDataJson,
    borderColor: 'rgba(0,0,255,1)',
    backgroundColor: 'rgba(0,0,255,0.5)',
    fill: true
  }
  ]
};

let yourOptions = {
  scales: {
    x: { // <-- v3.x now object "{", not array "[{" anymore
      type: 'timeseries', // <-- try "time" and "timeseries" to see difference
      time: {
        unit: 'day', // <-- set 'hour' / 'day' / 'week' / 'month' or 'year'
        displayFormats: {
          hour: 'h:mm a',
          day: 'ddd, MMM DD, YYYY',
          week: 'dddd',
          month: 'MMM'
        },
        tooltipFormat: 'dddd, MMM DD, YYYY' // <-- new in v3.x
      },
      ticks: {
        minRotation: 80, // avoiding overlapping of x-Axis ticks
        maxRotation: 90
      }
    },
    y: { // <-- v3.x now object "{", not array "[{" anymore
      ticks: {
        beginAtZero: true,
        callback: function (value) {
          if (Number.isInteger(value)) return value;
        }
      },
      suggestedMin: 0,
      // the data maximum used for determining the ticks is Math.max(dataMax, suggestedMax)
      suggestedMax: 10
    }
  }
};

const ctx = document.getElementById('chartJSContainer').getContext('2d');
const myChart = new Chart(ctx, {
  type: 'line',
  data: yourData,
  options: yourOptions
});

document.querySelector('#btnTime').addEventListener('click', () => {
  myChart.options.scales['x'].type = 'time';
  myChart.update();
});
document.querySelector('#btnTimeseries').addEventListener('click', () => {
  myChart.options.scales['x'].type = 'timeseries';
  myChart.update();
});

<!-- <script src="https://cdnjs.cloudflare.com/ajax/libs/Chart.js/2.9.4/Chart.js"></script> -->

<!-- Obtain the most recent version of Chart.js, currently at v3.5.1 -->
<script src="https://cdn.jsdelivr.net/npm/chart.js"></script>

<!-- To utilize x-Axis types 'time' or 'timeseries', additional libraries are required -->
<!-- (such as moment.js and its adapter) -->
<script src="https://cdnjs.cloudflare.com/ajax/libs/moment.js/2.29.1/moment.min.js"></script>
<script src="https://cdn.jsdelivr.net/npm/chartjs-adapter-moment"></script>

<button id='btnTime'>time</button>
<button id='btnTimeseries'>timeseries</button>

<canvas id="chartJSContainer" width="600" height="400"></canvas>

Establish a minimum threshold for movements in the line graph

Answer №1

Answer №2

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