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 charts – first 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.

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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

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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.

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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.

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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.

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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

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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).