Parallel coordinates chart

Device comparison chart

Compares many entities across several measurements at once. Every data key becomes a vertical axis, every entity becomes a line crossing all of them, so the shape of the group is visible at a glance and the entities that break it stand out.

Features

• One axis per data key, one line per entity, in the order the keys are configured
• Optional highlighting of entities that sit statistically far from the group on any axis
• Colour per entity, a single colour, or a gradient driven by the value on one axis
• Drag a range on any axis to keep only the lines that pass through it; drag it away to clear
• Optional legend; clicking an entry hides that entity
• Tooltip on hover with the entity name and every value with its units
• Reads telemetry and attributes, so a measured value can be compared against a rated one

Data keys

Any numeric keys, from two upwards. Each key becomes one axis, and axes are drawn in the order the keys appear in the datasource.

• any key (timeseries) — the latest reported value
• any key (attribute) — the current attribute value

Non-numeric values are ignored. Four to six keys read best; above seven the axis names start to be truncated.

Missing values

• A key that has no value on any entity yet: its axis is dropped and the footnote names it
• An entity missing a value on one of the remaining axes: its line is dropped and the footnote counts it, because a line with a gap reads as a different shape rather than as missing data

Configuration

Axes — direction (vertical axes side by side, or horizontal axes stacked); space above and below the extreme values, as a percentage of their span; whether the axis ends are snapped to round numbers, which keeps the scale still as new readings arrive; ticks per axis; colour and size of axis names and tick labels; axis line colour.

Lines — width, opacity, and whether the lines curve between axes. Colour comes from one of three modes: a palette (Default, Cool, Warm, Monochrome) giving each entity its own colour; a single colour for every line; or a gradient across one axis, set by data key name or label, with its own low, middle and high colours and an optional colour scale.

Outliers — off by default. When on, each entity is compared with the spread of the others on every axis, and any entity at least N standard deviations out is drawn in the highlight colour while the rest fade to the chosen opacity. The default of 2 marks roughly the furthest 5% of a normal group, 3 the furthest 0.3%. An axis on which every entity agrees has no spread and marks nobody.

Legend — off by default. Position (bottom, top, left, right), font, and text colour. Above 60 entities the legend is not drawn and the footnote says so.

Tooltip — on or off, font, text colour, and background. It appears on hover and lists the hovered entity with all of its values and units.

Widget title, background, padding and card size come from the widget’s own appearance settings.

Requirements

ECharts is declared as a widget resource and loads with the widget; nothing needs to be installed. If it cannot be reached, the card says so instead of rendering empty.