Select

Select arrays

Open a array for testing:

julia

using DGGS
p = open_dggs_pyramid("https://s3.bgc-jena.mpg.de:9000/dggs/datasets/modis")

DGGSPyramid
DGGS: DGGRID ISEA4H Q2DI ⬢
Levels: [2, 3, 4, 5, 6, 7, 8, 9, 10]
Non spatial axes:
  time 216 Dates.DateTime points
Arrays:
  lst (:time) K Union{Missing, Float32} 
  ndvi (:time) NDVI Union{Missing, Float32}

Select a ndvi at a given spatial resolution level:

julia

p[5]

DGGSLayer{5}
DGGS:	DGGRID ISEA4H Q2DI ⬢ at level 5
Non spatial axes:
  time 216 Dates.DateTime points
Arrays:
  lst (:time) K Union{Missing, Float32} 
  ndvi (:time) NDVI Union{Missing, Float32}

Select an array by its id:

julia

p[5].ndvi

DGGSArray{Union{Missing, Float32}, 5}
Name:		ndvi
Units:		NDVI
DGGS:		DGGRID ISEA4H Q2DI ⬢ at level 5
Attributes:	18
Non spatial axes:
  time 216 Dates.DateTime points

Additional filtering by any non-spatial axes e.g. Time still results in a DGGSArray:

julia

p[5].ndvi[Time=1]

DGGSArray{Union{Missing, Float32}, 5}
Name:		NDVI
Units:		NDVI
DGGS:		DGGRID ISEA4H Q2DI ⬢ at level 5
Attributes:	18
Non spatial axes:

Further filtering will return a YAXArray instead:

julia

p[5].ndvi[Time=1][q2di_n = 2]

┌ 16×16 YAXArray{Union{Missing, Float32}, 2} ┐
├────────────────────────────────────────────┴──────────── dims ┐
  ↓ q2di_i Sampled{Int64} 0:1:15 ForwardOrdered Regular Points,
  → q2di_j Sampled{Int64} 0:1:15 ForwardOrdered Regular Points
├───────────────────────────────────────────────────── metadata ┤
  Dict{String, Any} with 18 entries:
  "dggs_radius"           => 6.37101e6
  "long_name"             => "monthly NDVI CMG 0.05 Deg Monthly NDVI"
  "dggs_rotation_azimuth" => 0
  "scale_factor"          => 0.0001
  "dggs_rotation_lon"     => 11.25
  "dggs_id"               => "DGGRID ISEA4H Q2DI"
  "dggs_polygon"          => "hexagon"
  "dggs_level"            => 5
  "_FillValue"            => -9999.0
  "units"                 => "NDVI"
  "name"                  => "NDVI"
  "dggs_polyhedron"       => "icosahedron"
  "missing_value"         => -9999.0
  "add_offset"            => 0.0
  "dggs_projection"       => "isea"
  "dggs_rotation_lat"     => 58.2825
  "dggs_aperture"         => 4
  "dggs_index"            => "Q2DI"
├──────────────────────────────────────────────── loaded lazily ┤
  data size: 1.0 KB
└───────────────────────────────────────────────────────────────┘

Select cells and its neighbors

Select a single cell using geographical coordinates (lon, lat):

julia

a = p[6].ndvi
a[11.586, 50.927]

┌ 216-element YAXArray{Union{Missing, Float32}, 1} ┐
├──────────────────────────────────────────────────┴───────────────────── dims ┐
  ↓ time Sampled{Dates.DateTime} [2001-01-01T00:00:00, …, 2018-12-01T00:00:00] ForwardOrdered Irregular Points
├──────────────────────────────────────────────────────────────────── metadata ┤
  Dict{String, Any} with 18 entries:
  "dggs_radius"           => 6.37101e6
  "long_name"             => "monthly NDVI CMG 0.05 Deg Monthly NDVI"
  "dggs_rotation_azimuth" => 0
  "scale_factor"          => 0.0001
  "dggs_rotation_lon"     => 11.25
  "dggs_id"               => "DGGRID ISEA4H Q2DI"
  "dggs_polygon"          => "hexagon"
  "dggs_level"            => 6
  "_FillValue"            => -9999.0
  "units"                 => "NDVI"
  "name"                  => "NDVI"
  "dggs_polyhedron"       => "icosahedron"
  "missing_value"         => -9999.0
  "add_offset"            => 0.0
  "dggs_projection"       => "isea"
  "dggs_rotation_lat"     => 58.2825
  "dggs_aperture"         => 4
  "dggs_index"            => "Q2DI"
├─────────────────────────────────────────────────────────────── loaded lazily ┤
  data size: 864.0 bytes
└──────────────────────────────────────────────────────────────────────────────┘

Select the same cell using DGGS coordinates (n,i,j):

julia

a[3,2,30]

┌ 216-element YAXArray{Union{Missing, Float32}, 1} ┐
├──────────────────────────────────────────────────┴───────────────────── dims ┐
  ↓ time Sampled{Dates.DateTime} [2001-01-01T00:00:00, …, 2018-12-01T00:00:00] ForwardOrdered Irregular Points
├──────────────────────────────────────────────────────────────────── metadata ┤
  Dict{String, Any} with 18 entries:
  "dggs_radius"           => 6.37101e6
  "long_name"             => "monthly NDVI CMG 0.05 Deg Monthly NDVI"
  "dggs_rotation_azimuth" => 0
  "scale_factor"          => 0.0001
  "dggs_rotation_lon"     => 11.25
  "dggs_id"               => "DGGRID ISEA4H Q2DI"
  "dggs_polygon"          => "hexagon"
  "dggs_level"            => 6
  "_FillValue"            => -9999.0
  "units"                 => "NDVI"
  "name"                  => "NDVI"
  "dggs_polyhedron"       => "icosahedron"
  "missing_value"         => -9999.0
  "add_offset"            => 0.0
  "dggs_projection"       => "isea"
  "dggs_rotation_lat"     => 58.2825
  "dggs_aperture"         => 4
  "dggs_index"            => "Q2DI"
├─────────────────────────────────────────────────────────────── loaded lazily ┤
  data size: 864.0 bytes
└──────────────────────────────────────────────────────────────────────────────┘

A 3-ring and a 2-disk around a center cell

Select a 2-disk containing all neighboring cells that are at least k cells apart including a given center cell:

julia

a[11.586, 50.927, 1:2]

┌ 7×216 YAXArray{Union{Missing, Float32}, 2} ┐
├────────────────────────────────────────────┴─────────────────────────── dims ┐
  ↓ q2di_k Sampled{Int64} 1:7 ForwardOrdered Regular Points,
  → time   Sampled{Dates.DateTime} [2001-01-01T00:00:00, …, 2018-12-01T00:00:00] ForwardOrdered Irregular Points
├──────────────────────────────────────────────────────────────────── metadata ┤
  Dict{String, Any}()
├──────────────────────────────────────────────────────────── loaded in memory ┤
  data size: 5.91 KB
└──────────────────────────────────────────────────────────────────────────────┘

This will introduce a new dimension q2di_k iterating over all neighbors. The ordering of cells within this dimension is deterministic but not further specified.

Select a 3-ring of cells having the same distance to the center cell:

julia

a[11.586, 50.927, 3]

┌ 12×216 YAXArray{Union{Missing, Float32}, 2} ┐
├─────────────────────────────────────────────┴────────────────────────── dims ┐
  ↓ q2di_k Sampled{Int64} 1:12 ForwardOrdered Regular Points,
  → time   Sampled{Dates.DateTime} [2001-01-01T00:00:00, …, 2018-12-01T00:00:00] ForwardOrdered Irregular Points
├──────────────────────────────────────────────────────────────────── metadata ┤
  Dict{String, Any}()
├──────────────────────────────────────────────────────────── loaded in memory ┤
  data size: 10.12 KB
└──────────────────────────────────────────────────────────────────────────────┘

long and short syntax

Selection on both spatial and non-spatial dimensions can be performed using keyword-based arguments on pyramids, ndvis, and arrays:

julia

p[id=:ndvi, Time=1, level=5, lon=11.586, lat=50.927]

┌ 0-dimensional YAXArray{Union{Missing, Float32}, 0} ┐
├────────────────────────────────────────────────────┴ metadata ┐
  Dict{String, Any} with 18 entries:
  "dggs_radius"           => 6.37101e6
  "long_name"             => "monthly NDVI CMG 0.05 Deg Monthly NDVI"
  "dggs_rotation_azimuth" => 0
  "scale_factor"          => 0.0001
  "dggs_rotation_lon"     => 11.25
  "dggs_id"               => "DGGRID ISEA4H Q2DI"
  "dggs_polygon"          => "hexagon"
  "dggs_level"            => 5
  "_FillValue"            => -9999.0
  "units"                 => "NDVI"
  "name"                  => "NDVI"
  "dggs_polyhedron"       => "icosahedron"
  "missing_value"         => -9999.0
  "add_offset"            => 0.0
  "dggs_projection"       => "isea"
  "dggs_rotation_lat"     => 58.2825
  "dggs_aperture"         => 4
  "dggs_index"            => "Q2DI"
├──────────────────────────────────────────────── loaded lazily ┤
  data size: 4.0 bytes
└───────────────────────────────────────────────────────────────┘

which is equivalent to:

julia

p[5].ndvi[Time=1][11.586, 50.927]

┌ 0-dimensional YAXArray{Union{Missing, Float32}, 0} ┐
├────────────────────────────────────────────────────┴ metadata ┐
  Dict{String, Any} with 18 entries:
  "dggs_radius"           => 6.37101e6
  "long_name"             => "monthly NDVI CMG 0.05 Deg Monthly NDVI"
  "dggs_rotation_azimuth" => 0
  "scale_factor"          => 0.0001
  "dggs_rotation_lon"     => 11.25
  "dggs_id"               => "DGGRID ISEA4H Q2DI"
  "dggs_polygon"          => "hexagon"
  "dggs_level"            => 5
  "_FillValue"            => -9999.0
  "units"                 => "NDVI"
  "name"                  => "NDVI"
  "dggs_polyhedron"       => "icosahedron"
  "missing_value"         => -9999.0
  "add_offset"            => 0.0
  "dggs_projection"       => "isea"
  "dggs_rotation_lat"     => 58.2825
  "dggs_aperture"         => 4
  "dggs_index"            => "Q2DI"
├──────────────────────────────────────────────── loaded lazily ┤
  data size: 4.0 bytes
└───────────────────────────────────────────────────────────────┘

Select ​

Select arrays ​

Select cells and its neighbors ​

long and short syntax ​

Select

Select arrays

Select cells and its neighbors

long and short syntax