Whether a group of line series carries ranks rather than magnitudes.
A rank is a permutation, and that is what makes this decidable from the data
alone: every value is a whole place between first and last, no two
competitors hold the same place in the same period, and somebody comes first.
Counts and magnitudes fail all three the moment there is more than one of
them — two series that ever share a value are not a ranking, and a value
above the number of competitors is not a place any of them can hold.
Deliberately strict about what it will not read: a chart showing places 3
through 9 of a twenty-strong field is a genuine bump chart this answers false
for, and it stays a line chart rather than being sonified against a rank
range that does not include the leader it never draws.
Whether a group of line series carries ranks rather than magnitudes.
A rank is a permutation, and that is what makes this decidable from the data alone: every value is a whole place between first and last, no two competitors hold the same place in the same period, and somebody comes first. Counts and magnitudes fail all three the moment there is more than one of them — two series that ever share a value are not a ranking, and a value above the number of competitors is not a place any of them can hold.
Deliberately strict about what it will not read: a chart showing places 3 through 9 of a twenty-strong field is a genuine bump chart this answers
falsefor, and it stays a line chart rather than being sonified against a rank range that does not include the leader it never draws.