selector
The same parameter, picked from a list rather than dragged. For a quantity whose values are the ones the data holds and nothing in between: which country a chart shows, which of four models is fitted, which month. It is always discrete — there is nothing between its stops to stand in — so it declares no discrete: for anyone to say otherwise with. It is the one control whose values need not be numbers. options: of names, or over: a column of them, gives a parameter that holds a name; a mark's slice: over that same column then shows the rows carrying it, with no interpolation, because there is nothing between Brazil and China. A name never reaches an expression, which is why a selector is also the control whose parameter: is most often a word. To have the scene walk the choices instead, write cue.selector.
selector
#Attributes
parameterslider:a, and the whole scene's a from then on. One letter is the ordinary case, and the only one an expression can read: curve: a*x^2 reaches it by that letter. A word (selector:country) is for a parameter that never appears in a formula, and cannot be read in maths — to the expression parser country is a product of seven letters.parameter-namevarCan be written as shorthand: selector:valuenamelabeloverover: #pop.year. Its cells are the stops, their span is the range, and what they are decides the format — so range: is not consulted where this is given. A column of NAMES gives a parameter whose values are those names. This is the shape long-format data arrives in, and the shape a mark's slice: reads: the mark names the column, not the parameter, and the two meet at the column.columnformatnumbers, dates, months, weekdays, hours, weeks or names. Every one but the last places a value on its own number line — position 1…12 for a month, a fractional year for a date — so the range stays a pair of numbers and only the reading changes. names has no number line: the values are the data's own words. auto takes the kind from the column over: names, and is numeric where no column was named.autonumbersdatesmonthsweekdayshoursweeksnamesvaluesautorangeover: or options: gives the stops: those decide.[-10, 10]stepover:, the closest the data's own values come to each other, which is the spacing that can reach every row.defaultover:, the first value in the column. Where the stops are names this is an INDEX among them, since a name has no number line to sit on; writing the wanted one first in options: is the usual way to say which opens.starthiddenfalselockeditable: graph.lockedfalseoptionsoptions: [linear, log, logit], or options: [1, 2, 5, 10]. Numbers give a numeric parameter with stops no step: ladder can express; anything else gives names, and one unreadable entry makes the whole list names — [1, 2, many] is three labels, not a number line with a word on the end. It outranks over:, which outranks range:/step:; writing it beside over: is refused, as two claims about the same list.choices#Derived attributes
Computed while the element renders — read one with #id.name in attribute position or {{#id.name}} in prose, never set.
value#Allowed in
#Examples
selector:mode(options: [linear, log, logit])selector:n(options: [1, 2, 5, 10, 20]; name: sample size)selector:country(over: #pop.country)
bar(x: #pop.year; y: #pop.millions; slice: #pop.country)