## [2.11.0] - 2026-06-30
Inequality Curves: Lorenz / concentration curves and the Atkinson
index
(28 algorithms).
### Added
- **Inequality Curves (Lorenz & Atkinson)** (Equity group) — the
distributional view of any per-unit good (access score, green space
per
capita, income…), with an exportable curve to chart and a measure
that lets
you set how much you weight the worst-off.
- Outputs the **Lorenz curve** as a table — cumulative population
share vs
cumulative value share, bowing below the 45° line of equality —
and the
**Gini** coefficient (twice the area between them).
- Reports the **Atkinson index** at low/medium/high inequality
aversion
(ε = 0.5, 1, 2) and at your own ε: higher ε weights the lower tail
more,
so the index reads as the share of total value society would trade
to
equalise the distribution.
- A **rank field** (deprivation, income…) switches it to a
**concentration
curve and index**, revealing whether the value concentrates on the
advantaged or disadvantaged end (negative when it falls as rank
rises).
- `engine/equity.atkinson_index`, `lorenz_points`, `gini_from_lorenz`
and
`concentration_index` — pure NumPy, population-weighted; a new
group-coloured tool icon.
### Testing
- Engine unit checks grown to **216**; end-to-end assertions to
**166** on
QGIS 3.44 LTR and QGIS 4.0.2. The trapezoidal Gini is asserted equal
to the
mean-difference Gini, and Atkinson against hand-computed
geometric/harmonic
means.
yes
geo140195philo
2026-06-30T16:29:31.208875+00:00
3.22.0
4.99.0
None
no
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