Histogram Widget

Overview

Video

What Is the Histogram Widget?

The Histogram Widget is Datacake’s new, multi-purpose chart component for summarising numeric telemetry across many devices. It combines:

  • Bar charts – classic column view of each data source.

  • Interactive statistics table – min | max | average with live highlighting.

  • Pie chartsfirst time ever on Datacake! – for quick distribution insights.

  • Value Ranges – rule-based colouring (and optional grouping in Pie mode).

Use it to visualise anything from city-by-city temperatures to battery-level bands across your fleet.


Quick Start

Step
Action

1

Add Widget → choose Histogram

2

Give it a title (e.g. Temperature Histogram)

3

Open Data tab → add the telemetry fields you want to compare

4

(Optional) set a Unit (°C, %, V, …)

5

Fine-tune look & behaviour under Appearance and Value Ranges

6

Save and resize the widget on your dashboard


Data Configuration

Adding Data Sources

Each bar (or pie slice) starts with a Data Source: pick one or more device fields. Future releases will support semantic shortcuts (e.g. “All temperatures”) – for now, select manually.

Naming & Units

  • Rename each source for a readable legend label.

  • Add a Unit so the y-axis, tooltips and statistics table share a consistent suffix.


Appearance Options

Chart Type

Option
Use-case
Notes

Bar Chart (default)

Compare absolute values between sources

Shows value labels above each bar if enabled

Pie Chart

Show distribution (source-based or range-based)

First appearance on Datacake

Switch type anytime in Appearance → Chart Type.

Display Toggles

  • Show Statistics Table – reveals interactive Min/Max/Avg grid.

  • Show Values on Bars – numeric labels directly on bars.

  • Hide Background – transparent widget for dark dashboards.

Decimal Places

Control global rounding (0 – 4 decimals) for bars, tooltips and table cells.

Value Ranges

Value Ranges let you:

  1. Colorise bars or slices according to thresholds.

  2. Group devices into bands when Pie Chart mode is active.

Field
Description

Name

Friendly label (e.g. Cold, Warm, Extreme)

From / To

Inclusive numeric limits

Color

Hex picker for range colour

Enable them under Value Ranges → “Enable Value Ranges”.

Range Colouring (Bar Mode)

Bars keep their individual height (device value) but adopt the colour of the range they fall into – fast visual QA of outliers.

Range Grouping (Pie Mode) – Key Concept

Without ranges, a pie shows one slice per data source. With ranges enabled, the pie swaps to distribution mode:

  • Each slice is a range, not a device.

  • Slice size = number of devices inside that range (percentage shown on hover & in legend).

This turns the same telemetry into an instant “how many devices are cold / warm / hot?” insight.


Interactivity

  • Hover a bar → highlights corresponding row in the statistics table.

  • Hover a table row → flashes the matching bar.

  • Hover a pie slice → tooltip with range name + device count + percentage.

  • Supports real-time updates when the dashboard is in Live Data mode.


Best Practices & Tips

Scenario
Recommendation

Fleet health distribution

Use Pie + Value Ranges to spot clusters (e.g. battery 0–20 %, 20–50 %, …)

Comparing absolute sensor values

Stick to Bar with value labels and stats table

Many devices (> 20)

Ranges become essential – otherwise the legend gets crowded

Dark dashboards

Enable Hide Background and pick high-contrast range colours

Multi-metric page

Duplicate the widget, then edit Data tab only – ranges & styling carry over


FAQ

Q: Why does my pie chart still show device names instead of ranges?

A: Make sure Enable Value Ranges is toggled on and at least one range is defined.

Q: How are slice percentages calculated?

A: (Device count in range ÷ Total device count) × 100 %. Individual values are not summed in range mode.

Q: Can I disable the statistics table?

A: Yes – Appearance → toggle Show Statistics Table.

Q: Will semantic data selection be available?

A: Yes, upcoming releases will auto-suggest fields (e.g. all “temperature” sensors).

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