Curve Bump Chart

Data + Tableau + Me: How to Sigmoid Bump Chart (Spline?)

Suitable dataset:

rank of group in each year

rank	year	group (eg countries)
1	2001	Swizterland
2	2001	Japan
3	2001	Hong Kong
..
1	2009	Hong Kong
2	2009	Japan
3	2009	Swizterland

Sigmoid Curve

1. create “Path” from 1 to 49 and join it with the dataset
2. create following 8 cal. field:

//T

([Path]-25)/4

//Sigmoid

1/(1+EXP(1)^-[T])

//Year Order

[Year] - {MIN([Year])} //index across the years

//Path Order

(49*[Year Order])+[Path] //point 1-49 per year

//Year fake

([Path Order]/49) + 2000

//Rank 2 Setup IF MIN([Path]) = 49 THEN LOOKUP(MIN([Rank]),1) END

//Rank 2

IFNULL(WINDOW_MIN([Rank 2 Setup]), MIN([Rank]))

//Curve

MIN([Rank])+(([Rank 2] - MIN([Rank]))*MIN([Sigmoid]))

1. yearfake to column; change into dimension
2. curve to row; country to & year to detail mark
3. Table calculation of curve → nested cal. for both and rank2 setup → Rank2: Countries > Year > Yearfake; restarting every year rank2 setup: Countries > Year > Yearfake; restarting every countreis

Point on the curve

1. create cal. field:

//Dual Shape

FLOAT(MIN(IF [Path]=1 THEN [Rank] END))

1. add to row shelf and dual synchronised axis