degrees.coffee | |
|---|---|
_ = require 'underscore'
class Degrees | |
| A Factory Method Class | of: (given , base = true) ->
switch base
when true then new DegreesBase given
when 'lon', 'longitude' then new CelestialLongitude given
else throw "Unknown kind of #{base} degrees." |
| Alias for | lon: (given, rep) -> |
| Takes an optional representation - 1 for the Ram to 12 for the Fishes. | if rep?
if _.isNumber(rep) and 1 <= rep <= 12
rep = Math.floor rep
add = (rep - 1) * 30
if _.isNumber given then given += add
else if _.isArray given and _.isNumber given[0] then given[0] += add |
| The degrees and representation must be numbers / valid. | else throw "The given #{given} degrees can't be added to."
else throw "Invalid representation #{rep}."
@of given, 'lon' |
| Sometimes using more than one degrees instance within this module too. | degrees = new Degrees
class DegreesBase |
| Unacceptable initial value. | dec: NaN |
| Requirements to be overriden by sub-classes as needed. | abs: false # must be / remain absolute (i.e. a positive value) |
| Ensuring a | constructor: (@given) ->
if _.isNumber @given then @dec = @given |
| DMS: | else if _.isArray @given
unless 1 <= @given.length <= 3
throw "The given array must at least have degrees, and at most seconds." |
| TODO: figure out why the following validation isn't working: | |
| |
| Note: integers are expected, discarding aything after the decimal. | @dec = Math.floor(Math.abs @given[0])
@dec += Math.floor(Math.abs @given[1]) / 60 if @given.length > 1 # mins
@dec += Math.floor(Math.abs @given[2]) / 3600 if @given.length > 2 # secs
else throw "Unexpected '#{typeof(@given)}' type of degrees given." |
| The positive (i.e. absolute) angle - whole int or decimal. | if @abs then @dec = Math.abs @dec |
| Ensures the degrees are negative. Useful for geo-coordinates. This was introduced for easier instantiation with a dms array. The @pos opposite could also be added, but that means variable degrees... So far this is the only method besides the constructor(s) that modify @dec. Therefore a one-time-deal without undo. | neg: ->
unless @abs then @dec = 0 - Math.abs @dec
@ |
| Just so one can get the decimal degrees with a method call rather than
with | the: -> @dec |
| Radians. | rad: ->
@dec * Math.PI / 180 |
| Array of [sign, degrees, minutes, seconds] for the standard acronym. Note: that we can't do fractional seconds (as a result of not taking them). | dms: -> |
| Empty string for plus will make it easier to display. | n = if @dec < 0 then '-' else ''
dec = Math.abs @dec
d = Math.floor dec
m = Math.floor((dec * 60) % 60) # 0 <= m < 60
s = Math.floor((dec * 3600) % 60) # 0 <= s < 60
[ n, d, m, s ] |
| A string (with unicode characters after the degrees, minutes and seconds). Fist, but not least, it starts with '-' (minus) if negative. | str: ->
[ n, d, m, s ] = @dms()
"#{n}#{d}\u00B0#{m}\u2032#{s}\u2033"
unimplemented: (method) -> |
|
| throw "The wanted '#{method}' method is not implemented yet."
class CelestialLongitude extends DegreesBase |
| See DegreesBase. | abs: true # absolutely always positive |
| These are only for rep-based longitude, though alignment could be refactored for BaseDegrees as well - need to take into account variation of 1-3 digits. | aligns: false # set filler character to ' ' or '0' for dms() / str() alignment
representations: ['♈', '♉', '♊', '♋', '♌', '♍', '♎', '♏', '♐', '♑', '♒', '♓'] |
| Longitude degrees are special. | constructor: (@given) ->
super @given |
| Ensure [0..360] range, however the pure 0 can't be had. It throws off various calculations, think about doing the same for base... unless @dec is 0 # the only way to have 0 is be given a 0 (no longer true) | @dec %= 360 # smaller modulos can be done with `mod n` modification
@dec = 360 if @dec is 0 # exact multiples of 360 equal 360 degrees, again |
| Note that @rep aligns by default. Set to '' (empty string) if not wanted. | align: (fill = ' ') ->
fill = "#{fill}" if _.isNumber fill # so that 0 doesn't have to be quoted
@aligns = fill # take any value, but the useful are 0, space, '' or false
@ # chain-able |
| Longitude @dms function is special: * it cannot be negative (so it discards the sign) * it can be aligned with a prepended character - the [d,m,s] become strings The @aligns filling must be set (best by pre-chaining call of @align) and is consumed / cleared with @dms() use. | dms: ->
[n, d, m, s] = super()
if _.isString(@aligns)
@aligns = @aligns.charAt(0) if @aligns.length > 1
d = "#{@aligns}#{d}" if d < 10
m = "#{@aligns}#{m}" if m < 10
s = "#{@aligns}#{s}" if s < 10
@aligns = false
[d, m, s] |
| Is portion (or degree in modern parlance). | top: ->
portion = Math.ceil @dec
portion = 360 if portion is 0 # there is no zero portion (= whole circle)
portion
portion: ->
@top() |
| The 1 to 12 for image / representation (modern "sign" number). Request more and get a representation-first array, followed by that more, where more is a string that matches a method name (e.g. 'top', 'dms') for further getting the rest of the @dec degrees in a representation context. | rep: (more) ->
rep = if @dec is 0 or @dec is 360 then 12 else Math.ceil(@dec / 30)
switch more
when undefined then rep
when "sym" then @representations[rep - 1]
when "str"
rest = @dec - (rep - 1) * 30 |
| Pass on & reset the @aligns, or else align by default if not set. The usual false is ignored - so use blank '' in order to not align. | [a, @aligns] = [(if _.isString(@aligns) then @aligns else null), false]
[ d, m, s ] = degrees.lon(rest).align(a).dms()
"#{@representations[rep - 1]} #{d}\u00B0#{m}\u2032#{s}\u2033"
when "the", "top" then [rep, (@[more]() - (rep - 1) * 30)]
else throw "Unsupported: rep('#{more}')"
representation: (more) ->
@rep(more) |
| The 12th part higher-level representation (1 to 12 again). | _12: (exact = false) -> |
| is p12: -> #better? | @unimplemented('p12')
module.exports = degrees
|