DimensionalArrayTraits.jl

Abstract base package for dimensional arrays and their specific traits
Author JuliaGeo
Popularity
6 Stars
Updated Last
10 Months Ago
Started In
October 2019

DimensionalArrayTraits.jl

Abstract base package for dimensional arrays and their specific traits Note this is package currently in the discussion stage.

Requirements on spatial data/domain types from the user's perspective

It is proposed to add behind each point, a possible interface (from the user point of view)

  • Return coordinates lon/lat/depth/time (and arbitrary dimension) for a given index i,j,k,...
coord(A,:latitude,i,j,k) # or better coord(A,Lat(),i,j,k)  
lat(A,i,j,k) # for common dimension names
lat(A,j) # if grids are aligned with longitude/latitude/depth/time...; otherwise an error
lon
  • Return the value at a given index i,j,k... (the result is no longer georeferenced).
value(A,i,j,k)
  • Tell what each coordinate represent (is the 3rd dimension time or depth or something else?).
coordnames(x) # would return :longitude, :latitude, ... or Lon(), Lat()

Use the CF convention names (longitude, latitude, time, …)

  • Subsetting based on lon/lat/depth/time (and arbitrary dimension) bounding box
  • Irregular grid subsetting returns either: a masked array or a vector of points - need to decide which occurs on getinidex.
A[Lat(x), Lon(y), Time(At(t))]
  • Find the k nearest points for a given location
  • Integral over a raster (knowing the "volume" of each grid cell)
volume(A,i,j,k)
  • Is the cell value for the start, middle or (probably never) the end of the duration/span? Is it an average of the whole period or a specific point in the cell. These specifications should also generalise to any dimension type.
  • Categorical dimensions with no size and optional ordered/unordered status
  • Arrays can be plotted correctly using the grid information
plot(A[:,:,n])

Out-of-scope (at least initially)

  • units and other metadata

Implementation/Performance

  • Zero cost indexing (only works on regular grids?)
  • Lazy affine transformations on the data

Minimal interface to be implemented for different array types of spatial data

https://gist.github.com/meggart/e29e6381d9400ff789eefbccc109d6f9