[NTG-context] Use \unit for value and uncertainty

[Benjamin Buchmuller]

I know this is quite an old thread, but here is a minimal parser (\units with an “s”) that wraps around \digits and \unit to produce an acceptable output. 

As I frequently need to write ranges (or measures of uncertainty), I find it convenient to able to type

\units{4.0 to 5.0 centi meter} 

than 

\digits{4.0}\,to\,\unit{5.0 centi meter}.

Also, the parser will take care of exponents and bracket them accordingly. :D

ranges: keyword “to”: 4.0 – 5.0 cm
SEM:    keyword “se”: 4.5 ± 0.5 cm
SD:     keyword “sd”: 4.5 (0.5) cm

If no keyword is present, the default behaviour is \unit{…}.

The code is not perfect (and the level of abstraction potentially not yet sufficient to make it part of the phys-dim.mkiv source), but maybe helpful.

\starttext

\startluacode
	userdata = userdata or {}
	
	function userdata.units(input)
		
		tbl = string.explode(input)
		
		if tbl[2] == "to" then
			context.digits(tbl[1])
			context.phys_units_space()
			context("--")
			context.phys_units_space()
			context.unit(table.concat(tbl, " ", 3))
		elseif tbl[2] == "se" then
			local sx1 = string.split(tbl[1], "e")
			local sx2 = string.split(tbl[3], "e")
			if (sx1[2] == sx2[2]) and not (sx1[2] == nil) then
				context("(")
				context.digits(sx1[1])
				context.phys_units_space()
				context("±")
				context.phys_units_space()
				context.digits(sx2[1])
				context(")")
				context.digits("e" .. sx1[2])
				context.phys_units_space()
				context.unit(table.concat(tbl, " ", 4))
			else
				context.digits(tbl[1])
				context.phys_units_space()
				context("±")
				context.phys_units_space()
				context.unit(table.concat(tbl, " ", 3))
			end
		elseif tbl[2] == "sd" then
			local sx1 = string.split(tbl[1], "e")
			local sx2 = string.split(tbl[3], "e")
			if (sx1[2] == sx2[2]) and not (sx1[2] == nil) then
				context.digits(sx1[1])
				context.phys_units_space()
				context("(")
				context.digits(sx2[1])
				context(")")
				context.digits("e" .. sx1[2])
				context.phys_units_space()
				context.unit(table.concat(tbl, " ", 4))
			else
				context.digits(tbl[1])
				context.phys_units_space()
				context("(")
				context.digits(tbl[3])
				context(")")
				context.unit(table.concat(tbl, " ", 4))
			end
		else
			context.unit(table.concat(tbl, " "))
		end
		
	end
\stopluacode

\def\units#1{\ctxlua{userdata.units("#1")}}

Car 1 drives \units{4 to 5.2 kilo meter per hour}.

Car 2 drives \units{30.1 to 40.5 kilo meter per hour}.

Car 3 drives \units{40.= to 50.= kilo meter per hour}.

The average speed was \units{35,000 se 5000 meter per hour}.

The average speed was \units{35e3 se 0.5e3 meter per hour}.

The average speed was \units{35.2e3 se 5e2 meter per hour}.

\stoptext

The average speed was \units{35.2 se 5e2 meter per hour}.

The average speed was \units{_3.2 sd 5 meter per hour}.