About

Making a heatmap from custom datasets should be extremely easy. We are here to help you with that.

What's a heatmap? It is a data visualization technique that shows magnitude of a phenomenon as color in two dimensions^[1], and you can know it from GitHub user profile pages:

Installation

The Heatmap is distributed as Composer library via Packagist. To add it to your project, execute the following command:

composer require blumilksoftware/heatmap

Usage

You can use any set of data you want. By default, dates will be taken from "created_at" key of arrays or objects implementing \ArrayAccess interface. Builder accepts also objects implementing \Blumilk\HeatmapBuilder\Contracts\TimeGroupable contract with mandatory getTimeGroupableIndicator() method returning a string with proper date:

$data = [
    ["created_at" => "2025-11-01 00:00:00", /** (...) */],
    ["created_at" => "2025-11-03 00:00:00", /** (...) */],
    ["created_at" => "2025-11-16 00:00:00", /** (...) */],
    ["created_at" => "2025-11-16 00:00:00", /** (...) */],
    ["created_at" => "2025-11-18 00:00:00", /** (...) */],
    ["created_at" => "2025-11-19 00:00:00", /** (...) */],
];

Then create an instance of \Blumilk\HeatmapBuilder\HeatmapBuilder. By default, it will be working on day-based periods for last week from the moment you are calling it:

$builder = new HeatmapBuilder();
$result = $builder->build($data);

Method build() returns array of tiles that can be serialized into JSON with simple json_encode() function or any other serializer:

[
  {
    "label": "2025-11-16",
    "count": 2,
    "description": ""
  },
  {
    "label": "2025-11-17",
    "count": 0,
    "description": ""
  },
  {
    "label": "2025-11-18",
    "count": 1,
    "description": ""
  },
  {
    "label": "2025-11-19",
    "count": 1,
    "description": ""
  },
  {
    "label": "2025-11-20",
    "count": 0,
    "description": ""
  },
  {
    "label": "2025-11-21",
    "count": 0,
    "description": ""
  },
  {
    "label": "2025-11-22",
    "count": 0,
    "description": ""
  },
  {
    "label": "2025-11-23",
    "count": 0,
    "description": ""
  }
]

Customizing the Heatmap Builder watching period

By default, the HeatmapBuilder automatically sets its observation period to the last seven days if no custom period ($period) is provided during instantiation. This default behavior ensures a rolling seven-day view from the current day.

If you need to specify a custom period (e.g., the entire month of January), you can achieve this by explicitly passing a CarbonPeriod instance to the builder, as shown in the example below:

// Define a custom period for the entire month of January 2025
$period = CarbonPeriod::create(
    Carbon::parse('2025-01-01'),
    '1 day',
    Carbon::parse('2025-01-31')
);

// Instantiate the HeatmapBuilder with the custom period
$builder = new HeatmapBuilder(
    now: Carbon::now(),
    periodInterval: PeriodInterval::Daily,
    period: $period // Include the custom period
);

// Generate the heatmap data
$result = $builder->build($data);