dumbbell

Use to compare two values per category on one scale: before and after, plan and actual, two years. One row = one value: x category, series names the pair (required, exactly two values; the first seen is "from", the second "to"), y number. Keep input row order. The first value is a hollow dot, the second a filled dot, and the signed change prints at the right. A missing value leaves one dot and no rule. A repeated category/series pair → E_DUP_KEY. A third series value → E_UNKNOWN_FIELD. Negatives are fine.

Do not use for more than two values per category (bar grouped or line) or for a single value (bar).

x category · y number · series required, exactly two values

Rules. Keep row order. The first series value seen is drawn hollow, the second filled, joined by a rule; the signed change prints at the right. A missing value is a gap (one dot, no rule). A third value or no series → E_UNKNOWN_FIELD. An empty series cell → E_MISSING_VALUE. A repeated category/series pair → E_DUP_KEY.

Example

markvis: 2
type: dumbbell
title: Every line got faster after the signal upgrade
unit: min
x: line
y: minutes
series: period

line,period,minutes
Red,before,41
Red,after,36
Gold,before,39
Gold,after,35
Blue,before,33
Blue,after,31
Green,before,24
Green,after,23

Every line got faster after the signal upgrade

line	period	minutes
Red	before	41
Red	after	36
Gold	before	39
Gold	after	35
Blue	before	33
Blue	after	31
Green	before	24
Green	after	23

When the block is wrong

The rows stay, with one line that names the error.

markvis: 2
type: dumbbell
title: Three periods
x: line
y: minutes
series: period

line,period,minutes
Red,before,41
Red,after,36
Red,later,34

line	period	minutes
Red	before	41
Red	after	36
Red	later	34

E_UNKNOWN_FIELD: dumbbell needs exactly two period values (got 3)

Generated from packages/types/dumbbell/ and the type's row in SPEC.md.