SwissEphemeris.ChartUtils

Utility functions for chart drawing functionality. Uses the C code shared by the swiss ephemeris authors in the official mailing list: https://groups.io/g/swisseph/message/5568

Documentation

data GlyphInfo a

Information about a glyph (planet or some other object one intends to render within a circular chart) indicating suggested position and scale as decided by gravGroup or gravGroup2 to minimize collisions without affecting the sequence of a list of objects, or the sectors within which they may be grouped.

Constructors

GlyphInfo

Fields

• originalPosition :: Double

  the original position, before correction

• glyphSize :: (Double, Double)

  lsize,rsize: original size, in degrees, from the center extending to the left and the right, respectively.

• placedPosition :: Double

  position decided by the algorithm, in degrees

• sectorNumber :: Int

  sector assigned; should be the same as the original

• sequenceNumber :: Int

  position in sequence, should also be preserved

• levelNumber :: Int

  if allowing for multiple concentric levels, which level is this supposed to be on.

• glyphScale :: Double

  percentage of actual size it should be resized to fit, as per the algorithm's recommendation.

• extraData :: a

  arbitrary data. For PlanetGlyphInfo, this is a Planet.

Instances

Eq a => Eq (GlyphInfo a)

Defined in SwissEphemeris.ChartUtils

Methods

(==) :: GlyphInfo a -> GlyphInfo a -> Bool

(/=) :: GlyphInfo a -> GlyphInfo a -> Bool

Show a => Show (GlyphInfo a)

Defined in SwissEphemeris.ChartUtils

Methods

showsPrec :: Int -> GlyphInfo a -> ShowS

show :: GlyphInfo a -> String

showList :: [GlyphInfo a] -> ShowS

type PlanetGlyphInfo = GlyphInfo Planet

GlyphInfo specialized to carry Planet names as its extraData.

glyphPlanet :: PlanetGlyphInfo -> Planet

Convenience alias for the extraData accessor, get the Planet conveyed along a glyph info.

cuspsToSectors :: [HouseCusp] -> [Double]

This function does a little bit of insider trading: given N cusps, returns N+1 sectors; where the last sector is an "impossible" position beyond 360, that sets the end of the last sector as the first sector's beginning, beyond one turn. That way, any body occurring in the last sector will exist between sectors[N-1] and sectors[N]. I've been using this as the "linearization" approach for the sectors required by gravGroup, but one may choose something different.

gravGroup

Arguments

:: HasEclipticLongitude a

=> (Double, Double)

lwidth, rwidth

-> [(Planet, a)]

list of pre-calculated positions

-> [Double]

list of "sectors" (e.g. house cusps + end of last cusp)

-> Either String [PlanetGlyphInfo]

Given dimensions, planet positions and "sectors" within which the planets are meant to be drawn as glyphs, return a list pairing each position with a PlanetGlyphInfo that not only remembers the position's planet, it's guaranteed to place it in the same sector and sequence it started in, but moved as to avoid colliding with other nearby planets or sector boundaries.

Note that "sectors" are usually cusps, but one must take that they're sorted or "linearized": no sector should jump over 0/360, and the last sector should mark the "end" of the circle. I use cuspsToSectors on cusps obtained from the main module's cusp calculation functionality and that seems to ensure that sectors are adequately monotonic and not truncated, but one would be wise to take heed to the swiss ephemeris author's notes, too: https://groups.io/g/swisseph/message/5568

gravGroupEasy :: HasEclipticLongitude a => Double -> [(Planet, a)] -> [HouseCusp] -> Either String [PlanetGlyphInfo]

Easy version of gravGroup that assumes:

• Glyphs are square/symmetrical, so the left and right widths are just half of the provided width, each.
• The provided cusps can be "linearized" by the naïve approach of cuspsToSectors

gravGroup2

Arguments

:: HasEclipticLongitude a

=> (Double, Double)

lwidth, rwidth

-> [(Planet, a)]

list of pre-calculated positions

-> [Double]

list of "sectors" (e.g. house cusps + end of last cusp) (can be empty, indicating that we're working in a non-subdivided circle.)

-> Bool

allow planets to be moved up or down a level?

-> Either String [PlanetGlyphInfo]

Same semantics and warnings as gravGroup, but allows a couple of things for more advanced (or crowded) applications:

• Can send an empty list of sectors, to indicate that there's no subdivisions in the circle.
• Can specify if planets can be pushed to an "inner" level if they're too crowded in their assigned sector. Useful when drawing several objects in a chart with many/tight sectors.

With a non-empty list of sectors, and not allowing shifting, this is essentially a slightly slower version of gravGroup.

gravGroup2Easy :: HasEclipticLongitude a => Double -> [(Planet, a)] -> [HouseCusp] -> Bool -> Either String [PlanetGlyphInfo]

Easy version of gravGroup2, same provisions as gravGroupEasy