BehaviourComposer: ignore everything before this. Draws a Lorenz curve that visualises the distribution of wealth. It also computes the Gini coefficient which measures the inequality of the distribution. Note that this requires a graphing area (default name is "Wealth Distribution" ). It can be specified using Empty Lorenz curve.Begin micro-behaviour: Begin description: Draw Lorenz curve and update Gini coefficient. End description
Begin NetLogo code: substitute-text-area-for population-expression all-individuals substitute-text-area-for wealth-expression my-wealth substitute-text-area-for pen-color-expression round time mod 145 substitute-text-area-for lorenz-plot-name Wealth Distribution let population population-expression let wealth-attribute "wealth-expression" let population-count count population if population-count > 2 [ set-current-plot "lorenz-plot-name" auto-plot-off ; draw the perfectly equitable distribution first set-plot-pen-color 0 set-plot-x-range 0 100 set-plot-y-range 0 100 plot-pen-up plotxy 0 0 plot-pen-down plotxy 100 100 plotxy 0 0 set-plot-pen-color pen-color-expression let individuals-by-wealth sort-on [runresult wealth-attribute] population let total-wealth sum [runresult wealth-attribute] of population if total-wealth = 0 [stop] let one-percent-of-the-population population-count / 100 let percent-of-population 0 let gini-coefficient 0 while [percent-of-population < 100] [let agents-in-percent-of-population sublist individuals-by-wealth 0 round (percent-of-population * one-percent-of-the-population) let wealth-of-percent-of-population 0 forEach agents-in-percent-of-population [set wealth-of-percent-of-population wealth-of-percent-of-population + [runresult wealth-attribute] of ?] let percent-of-wealth wealth-of-percent-of-population * 100 / total-wealth set gini-coefficient gini-coefficient + percent-of-population - percent-of-wealth plotxy percent-of-population percent-of-wealth set percent-of-population percent-of-population + 1] set my-gini-coefficient gini-coefficient / 5050] End NetLogo code ## VariantsYou can specify the population by editing the first text area. The second text area specifies what attribute of individuals is used comparisons. The third text area specifies the color of the plotting pen.
## How this worksAfter drawing the black diagonal line representing the equitable distribution it then picks a new pen colour and draws the Lorenz curve. It does this by sorting all the individuals by wealth and computing what percentage of the total that each percentile of the poorer individuals posses. While doing this it also computes the Gini coefficient by approximating it by summing the 100 rectangles between the Lorenz curve and the equitable distribution and dividing that by the area under the diagonal line (which is the sum of 1, 2, 3, ..., 98, 99, 100 or 5050). ## Related micro-behavioursThis needs an Empty Lorenz curve to specify an area where the curve is drawn.
## HistoryDraw Lorenz curve was rewritten by Ken Kahn on 27 January 2012 BehaviourComposer: ignore everything after this. |