Lookups
DimensionalData.Dimensions.Lookups Module
LookupsModule for Lookups and Selectors used in DimensionalData.jl
Lookup defines traits and AbstractArray wrappers that give specific behaviours for a lookup index when indexed with Selector.
For example, these allow tracking over array order so fast indexing works even when the array is reversed.
To load Lookup types and methods into scope:
using DimensionalData
using DimensionalData.LookupsDimensionalData.Dimensions.Lookups.Lookup Type
LookupTypes defining the behaviour of a lookup index, how it is plotted and how Selectors like Between work.
A Lookup may be NoLookup indicating that there are no lookup values, Categorical for ordered or unordered categories, or a Sampled index for Points or Intervals.
DimensionalData.Dimensions.Lookups.Aligned Type
Aligned <: LookupAbstract supertype for Lookups where the lookup is aligned with the array axes.
This is by far the most common supertype for Lookup.
DimensionalData.Dimensions.Lookups.AbstractSampled Type
AbstractSampled <: AlignedAbstract supertype for Lookups where the lookup is aligned with the array, and is independent of other dimensions. Sampled is provided by this package.
AbstractSampled must have order, span and sampling fields, or a rebuild method that accepts them as keyword arguments.
DimensionalData.Dimensions.Lookups.Sampled Type
Sampled <: AbstractSampled
Sampled(data::AbstractVector, order::Order, span::Span, sampling::Sampling, metadata)
Sampled(data=AutoValues(); order=AutoOrder(), span=AutoSpan(), sampling=Points(), metadata=NoMetadata())A concrete implementation of the Lookup AbstractSampled. It can be used to represent Points or Intervals.
Sampled is capable of representing gridded data from a wide range of sources, allowing correct bounds and Selectors for points or intervals of regular, irregular, forward and reverse lookups.
On AbstractDimArray construction, Sampled lookup is assigned for all lookups of AbstractRange not assigned to Categorical.
Arguments
data: AnAbstractVectorof lookup values, matching the length of the curresponding array axis.order:Order) indicating the order of the lookup,AutoOrderby default, detected from the order ofdatato beForwardOrdered,ReverseOrderedorUnordered. These can be provided explicitly if they are known and performance is important.span: indicates the size of intervals or distance between points, and will be set toRegularforAbstractRangeandIrregularforAbstractArray, unless assigned manually.sampling: is assigned toPoints, unless set toIntervalsmanually. UsingIntervalswill change the behaviour ofboundsandSelectorss to take account for the full size of the interval, rather than the point alone.metadata: aDictorMetadatawrapper that holds any metadata object adding more information about the array axis - useful for extending DimensionalData for specific contexts, like geospatial data in Rasters.jl. By default it isNoMetadata().
Example
Create an array with Interval sampling, and Regular span for a vector with known spacing.
We set the locus of the Intervals to Start specifying that the lookup values are for the locus at the start of each interval.
using DimensionalData, DimensionalData.Lookups
x = X(Sampled(100:-20:10; sampling=Intervals(Start())))
y = Y(Sampled([1, 4, 7, 10]; span=Regular(3), sampling=Intervals(Start())))
A = ones(x, y)
# output
┌ 5×4 DimArray{Float64, 2} ┐
├──────────────────────────┴───────────────────────────────────────── dims ┐
↓ X Sampled{Int64} 100:-20:20 ReverseOrdered Regular Intervals{Start},
→ Y Sampled{Int64} [1, 4, 7, 10] ForwardOrdered Regular Intervals{Start}
└──────────────────────────────────────────────────────────────────────────┘
↓ → 1 4 7 10
100 1.0 1.0 1.0 1.0
80 1.0 1.0 1.0 1.0
60 1.0 1.0 1.0 1.0
40 1.0 1.0 1.0 1.0
20 1.0 1.0 1.0 1.0DimensionalData.Dimensions.Lookups.AbstractCyclic Type
AbstractCyclic <: AbstractSampledAn abstract supertype for cyclic lookups.
These are AbstractSampled lookups that are cyclic for Selectors.
DimensionalData.Dimensions.Lookups.Cyclic Type
Cyclic <: AbstractCyclic
Cyclic(data; order=AutoOrder(), span=AutoSpan(), sampling=Points(), metadata=NoMetadata(), cycle)A Cyclic lookup is similar to Sampled but out of range Selectors At, Near, Contains will cycle the values to typemin or typemax over the length of cycle. Where and .. work as for Sampled.
This is useful when we are using mean annual datasets over a real time-span, or for wrapping longitudes so that -360 and 360 are the same.
Arguments
data: AnAbstractVectorof lookup values, matching the length of the curresponding array axis.order:Order) indicating the order of the lookup,AutoOrderby default, detected from the order ofdatato beForwardOrdered,ReverseOrderedorUnordered. These can be provided explicitly if they are known and performance is important.span: indicates the size of intervals or distance between points, and will be set toRegularforAbstractRangeandIrregularforAbstractArray, unless assigned manually.sampling: is assigned toPoints, unless set toIntervalsmanually. UsingIntervalswill change the behaviour ofboundsandSelectorss to take account for the full size of the interval, rather than the point alone.metadata: aDictorMetadatawrapper that holds any metadata object adding more information about the array axis - useful for extending DimensionalData for specific contexts, like geospatial data in Rasters.jl. By default it isNoMetadata().cycle: the length of the cycle. This does not have to exactly match the data, thestepsize isWeek(1)the cycle can beYears(1).
Notes
If you use dates and e.g. cycle over a
Year, every year will have the number and spacing ofWeeks andDays as the cycle year. UsingAtmay not be reliable in terms of exact dates, as it will be applied to the specified date plus or minusnyears.Indexing into a
Cycledwith anyAbstractArrayorAbstractRangewill return aSampledas the full cycle is likely no longer available...orBetweenselectors do not work in a cycled way: they work as forSampled. This may change in future to return cycled values, but there are problems with this, such as leap years breaking correct date cycling of a single year. If you actually need this behaviour, please make a GitHub issue.
DimensionalData.Dimensions.Lookups.AbstractCategorical Type
AbstractCategorical <: AlignedLookups where the values are categories.
Categorical is the provided concrete implementation. But this can easily be extended, all methods are defined for AbstractCategorical.
All AbstractCategorical must provide a rebuild method with data, order and metadata keyword arguments.
DimensionalData.Dimensions.Lookups.Categorical Type
Categorical <: AbstractCategorical
Categorical(o::Order)
Categorical(; order=Unordered())A Lookup where the values are categories.
This will be automatically assigned if the lookup contains AbstractString, Symbol or Char. Otherwise it can be assigned manually.
Order will be determined automatically where possible.
Arguments
data: AnAbstractVectormatching the length of the corresponding array axis.order:Order) indicating the order of the lookup,AutoOrderby default, detected from the order ofdatato beForwardOrdered,ReverseOrderedorUnordered. Can be provided if this is known and performance is important.metadata: aDictorMetadatawrapper that holds any metadata object adding more information about the array axis - useful for extending DimensionalData for specific contexts, like geospatial data in Rasters.jl. By default it isNoMetadata().
Example
Create an array with [Interval] sampling.
using DimensionalData
ds = X(["one", "two", "three"]), Y([:a, :b, :c, :d])
A = DimArray(rand(3, 4), ds)
Dimensions.lookup(A)
# output
Categorical{String} ["one", "two", "three"] Unordered,
Categorical{Symbol} [:a, :b, :c, :d] ForwardOrderedDimensionalData.Dimensions.Lookups.Unaligned Type
Unaligned <: LookupAbstract supertype for Lookup where the lookup is not aligned to the grid.
Indexing an Unaligned with Selectors must provide all other Unaligned dimensions.
DimensionalData.Dimensions.Lookups.Transformed Type
Transformed <: Unaligned
Transformed(f, dim::Dimension; metadata=NoMetadata())Lookup that uses an affine transformation to convert dimensions from dims(lookup) to dims(array). This can be useful when the dimensions are e.g. rotated from a more commonly used axis.
Any function can be used to do the transformation, but transformations from CoordinateTransformations.jl may be useful.
Arguments
f: transformation functiondim: a dimension to transform to.
Keyword Arguments
metadata:
Example
using DimensionalData, DimensionalData.Lookups, CoordinateTransformations
m = LinearMap([0.5 0.0; 0.0 0.5])
A = [1 2 3 4
5 6 7 8
9 10 11 12];
da = DimArray(A, (X(Transformed(m)), Y(Transformed(m))))
da[X(At(6.0)), Y(At(2.0))]
# output
9DimensionalData.Dimensions.MergedLookup Type
MergedLookup <: Lookup
MergedLookup(data, dims; [metadata])A Lookup that holds multiple combined dimensions.
MergedLookup can be indexed with Selectors like At, Between, and Where although Near has undefined meaning.
Arguments
data: AVectorofTuple.dims: ATupleofDimensionindicating the dimensions in the tuples indata.
Keywords
metadata: aDictorMetadataobject to attach dimension metadata.
DimensionalData.Dimensions.Lookups.NoLookup Type
NoLookup <: Lookup
NoLookup()A Lookup that is identical to the array axis. Selectors can't be used on this lookup.
Example
Defining a DimArray without passing lookup values to the dimensions, it will be assigned NoLookup:
using DimensionalData
A = DimArray(rand(3, 3), (X, Y))
Dimensions.lookup(A)
# output
NoLookup, NoLookupWhich is identical to:
using .Lookups
A = DimArray(rand(3, 3), (X(NoLookup()), Y(NoLookup())))
Dimensions.lookup(A)
# output
NoLookup, NoLookupDimensionalData.Dimensions.Lookups.AutoLookup Type
AutoLookup <: Lookup
AutoLookup()
AutoLookup(values=AutoValues(); kw...)Automatic Lookup, the default lookup. It will be converted automatically to another Lookup when it is possible to detect it from the lookup values.
Keywords will be used in the detected Lookup constructor.
DimensionalData.Dimensions.Lookups.AutoValues Type
AutoValuesDetect Lookup values from the context. This is used in NoLookup to simply use the array axis as the index when the array is constructed, and in set to change the Lookup type without changing the index values.
The generic value getter val
DimensionalData.Dimensions.Lookups.val Function
val(x)
val(dims::Tuple) => TupleReturn the contained value of a wrapper object.
dims can be Dimension, Dimension types, or Symbols for Dim{Symbol}.
Objects that don't define a val method are returned unaltered.
Lookup methods:
DimensionalData.Dimensions.Lookups.bounds Function
bounds(xs, [dims::Tuple]) => Tuple{Vararg{Tuple{T,T}}}
bounds(xs::Tuple) => Tuple{Vararg{Tuple{T,T}}}
bounds(x, dim) => Tuple{T,T}
bounds(dim::Union{Dimension,Lookup}) => Tuple{T,T}Return the bounds of all dimensions of an object, of a specific dimension, or of a tuple of dimensions.
If bounds are not known, one or both values may be nothing.
dims can be a Dimension, a dimension type, or a tuple of either.
DimensionalData.Dimensions.Lookups.hasselection Function
hasselection(x, selector) => Bool
hasselection(x, selectors::Tuple) => BoolCheck if indexing into x with selectors can be performed, where x is some object with a dims method, and selectors is a Selector or Dimension or a tuple of either.
DimensionalData.Dimensions.Lookups.sampling Function
sampling(x, [dims::Tuple]) => Tuple
sampling(x, dim) => Sampling
sampling(xs::Tuple) => Tuple{Vararg{Sampling}}
sampling(x:Union{Dimension,Lookup}) => SamplingReturn the Sampling for each dimension.
Second argument dims can be Dimensions, Dimension types, or Symbols for Dim{Symbol}.
DimensionalData.Dimensions.Lookups.span Function
span(x, [dims::Tuple]) => Tuple
span(x, dim) => Span
span(xs::Tuple) => Tuple{Vararg{Span,N}}
span(x::Union{Dimension,Lookup}) => SpanReturn the Span for each dimension.
Second argument dims can be Dimensions, Dimension types, or Symbols for Dim{Symbol}.
DimensionalData.Dimensions.Lookups.order Function
order(x, [dims::Tuple]) => Tuple
order(xs::Tuple) => Tuple
order(x::Union{Dimension,Lookup}) => OrderReturn the Ordering of the dimension lookup for each dimension: ForwardOrdered, ReverseOrdered, or Unordered
Second argument dims can be Dimensions, Dimension types, or Symbols for Dim{Symbol}.
DimensionalData.Dimensions.Lookups.locus Function
locus(x, [dims::Tuple]) => Tuple
locus(x, dim) => Locus
locus(xs::Tuple) => Tuple{Vararg{Locus,N}}
locus(x::Union{Dimension,Lookup}) => LocusReturn the Position of lookup values for each dimension.
Second argument dims can be Dimensions, Dimension types, or Symbols for Dim{Symbol}.
DimensionalData.Dimensions.Lookups.shiftlocus Function
shiftlocus(locus::Locus, x)Shift the values of x from the current locus to the new locus.
We only shift Sampled, Regular or Explicit, Intervals.
Selectors
DimensionalData.Dimensions.Lookups.Selector Type
SelectorAbstract supertype for all selectors.
Selectors are wrappers that indicate that passed values are not the array indices, but values to be selected from the dimension lookup, such as DateTime objects for a Ti dimension.
Selectors provided in DimensionalData are:
Note: Selectors can be modified using:
Not: as inNot(At(x))
And IntervalSets.jl Interval can be used instead of Between
..IntervalOpenIntervalClosedInterval
DimensionalData.Dimensions.Lookups.IntSelector Type
IntSelector <: SelectorAbstract supertype for Selectors that return a single Int index.
IntSelectors provided by DimensionalData are:
DimensionalData.Dimensions.Lookups.ArraySelector Type
ArraySelector <: SelectorAbstract supertype for Selectors that return an AbstractArray.
ArraySelectors provided by DimensionalData are:
DimensionalData.Dimensions.Lookups.At Type
At <: IntSelector
At(x; atol=nothing, rtol=nothing)
At(a, b; kw...)Selector that exactly matches the value on the passed-in dimensions, or throws an error. For ranges and arrays, every intermediate value must match an existing value - not just the end points.
x can be any value to select a single index, or a Vector of values to select vector of indices. If two values a and b are used, the range between them will be selected.
Keyword atol is passed to isapprox.
Example
using DimensionalData
A = DimArray([1 2 3; 4 5 6], (X(10:10:20), Y(5:7)))
A[X(At(20)), Y(At(6))]
# output
5DimensionalData.Dimensions.Lookups.Near Type
Near <: IntSelector
Near(x)
Near(a, b)Selector that selects the nearest index to x.
With Points this is simply the lookup values nearest to the x, however with Intervals it is the interval center nearest to x. This will be offset from the index value for Start and End locus.
x can be any value to select a single index, or a Vector of values to select vector of indices. If two values a and b are used, the range between the nearsest value to each of them will be selected.
Example
using DimensionalData
A = DimArray([1 2 3; 4 5 6], (X(10:10:20), Y(5:7)))
A[X(Near(23)), Y(Near(5.1))]
# output
4DimensionalData.Dimensions.Lookups.Between Type
Between <: ArraySelector
Between(a, b)Depreciated: use a..b instead of Between(a, b). Other Interval objects from IntervalSets.jl, like `OpenInterval(a, b) will also work, giving the correct open/closed boundaries.
Between will e removed in future to avoid clashes with DataFrames.Between.
Selector that retrieve all indices located between 2 values, evaluated with >= for the lower value, and < for the upper value. This means the same value will not be counted twice in 2 adjacent Between selections.
For Intervals the whole interval must be lie between the values. For Points the points must fall between the values. Different Sampling types may give different results with the same input - this is the intended behaviour.
Between for Irregular intervals is a little complicated. The interval is the distance between a value and the next (for Start locus) or previous (for End locus) value.
For Center, we take the mid point between two index values as the start and end of each interval. This may or may not make sense for the values in your index, so use Between with Irregular Intervals(Center()) with caution.
Example
using DimensionalData
A = DimArray([1 2 3; 4 5 6], (X(10:10:20), Y(5:7)))
A[X(Between(15, 25)), Y(Between(4, 6.5))]
# output
┌ 1×2 DimArray{Int64, 2} ┐
├────────────────────────┴───────────────────────────── dims ┐
↓ X Sampled{Int64} 20:10:20 ForwardOrdered Regular Points,
→ Y Sampled{Int64} 5:6 ForwardOrdered Regular Points
└────────────────────────────────────────────────────────────┘
↓ → 5 6
20 4 5DimensionalData.Dimensions.Lookups.Touches Type
Touches <: ArraySelector
Touches(a, b)Selector that retrieves all indices touching the closed interval 2 values, for the maximum possible area that could interact with the supplied range.
This can be better than .. when e.g. subsetting an area to rasterize, as you may wish to include pixels that just touch the area, rather than those that fall within it.
Touches is different to using closed intervals when the lookups also contain intervals - if any of the intervals touch, they are included. With .. they are discarded unless the whole cell interval falls inside the selector interval.
Example
using DimensionalData
A = DimArray([1 2 3; 4 5 6], (X(10:10:20), Y(5:7)))
A[X(Touches(15, 25)), Y(Touches(4, 6.5))]
# output
┌ 1×2 DimArray{Int64, 2} ┐
├────────────────────────┴───────────────────────────── dims ┐
↓ X Sampled{Int64} 20:10:20 ForwardOrdered Regular Points,
→ Y Sampled{Int64} 5:6 ForwardOrdered Regular Points
└────────────────────────────────────────────────────────────┘
↓ → 5 6
20 4 5DimensionalData.Dimensions.Lookups.Contains Type
Contains <: IntSelector
Contains(x)
Contains(a, b)Selector that selects the interval the value is contained by. If the interval is not present in the lookup, an error will be thrown.
Can only be used for Intervals or Categorical. For Categorical it falls back to using At. Contains should not be confused with Base.contains - use Where(contains(x)) to check for if values are contain in categorical values like strings.
x can be any value to select a single index, or a Vector of values to select vector of indices. If two values a and b are used, the range between them will be selected.
Example
using DimensionalData; const DD = DimensionalData
dims_ = X(10:10:20; sampling=DD.Intervals(DD.Center())),
Y(5:7; sampling=DD.Intervals(DD.Center()))
A = DimArray([1 2 3; 4 5 6], dims_)
A[X(Contains(8)), Y(Contains(6.8))]
# output
3DimensionalData.Dimensions.Lookups.Where Type
Where <: ArraySelector
Where(f::Function)Selector that filters a dimension lookup by any function that accepts a single value and returns a Bool.
Example
using DimensionalData
A = DimArray([1 2 3; 4 5 6], (X(10:10:20), Y(19:21)))
A[X(Where(x -> x > 15)), Y(Where(x -> x in (19, 21)))]
# output
┌ 1×2 DimArray{Int64, 2} ┐
├────────────────────────┴────────────────────────────── dims ┐
↓ X Sampled{Int64} [20] ForwardOrdered Irregular Points,
→ Y Sampled{Int64} [19, 21] ForwardOrdered Irregular Points
└─────────────────────────────────────────────────────────────┘
↓ → 19 21
20 4 6DimensionalData.Dimensions.Lookups.All Type
All <: Selector
All(selectors::Selector...)Selector that combines the results of other selectors. The indices used will be the union of all result sorted in ascending order.
Example
using DimensionalData, Unitful
dimz = X(10.0:20:200.0), Ti(1u"s":5u"s":100u"s")
A = DimArray((1:10) * (1:20)', dimz)
A[X=All(At(10.0), At(50.0)), Ti=All(1u"s"..10u"s", 90u"s"..100u"s")]
# output
┌ 2×4 DimArray{Int64, 2} ┐
├────────────────────────┴─────────────────────────────────────────────── dims ┐
↓ X Sampled{Float64} [10.0, 50.0] ForwardOrdered Irregular Points,
→ Ti Sampled{Unitful.Quantity{Int64, 𝐓, Unitful.FreeUnits{(s,), 𝐓, nothing}}} [1 s, 6 s, 91 s, 96 s] ForwardOrdered Irregular Points
└──────────────────────────────────────────────────────────────────────────────┘
↓ → 1 s 6 s 91 s 96 s
10.0 1 2 19 20
50.0 3 6 57 60Lookup traits
DimensionalData.Dimensions.Lookups.LookupTrait Type
LookupTraitAbstract supertype of all traits of a Lookup.
These modify the behaviour of the lookup index.
The term "Trait" is used loosely - these may be fields of an object of traits hard-coded to specific types.
Order
DimensionalData.Dimensions.Lookups.Order Type
Order <: LookupTraitTraits for the order of a Lookup. These determine how searchsorted finds values in the index, and how objects are plotted.
DimensionalData.Dimensions.Lookups.Ordered Type
Ordered <: OrderSupertype for the order of an ordered Lookup, including ForwardOrdered and ReverseOrdered.
DimensionalData.Dimensions.Lookups.ForwardOrdered Type
ForwardOrdered <: Ordered
ForwardOrdered()Indicates that the Lookup index is in the normal forward order.
DimensionalData.Dimensions.Lookups.ReverseOrdered Type
ReverseOrdered <: Ordered
ReverseOrdered()Indicates that the Lookup index is in the reverse order.
DimensionalData.Dimensions.Lookups.Unordered Type
Unordered <: Order
Unordered()Indicates that Lookup is unordered.
This means the index cannot be searched with searchsortedfirst or similar optimised methods - instead it will use findfirst.
DimensionalData.Dimensions.Lookups.AutoOrder Type
AutoOrder <: Order
AutoOrder()Specifies that the Order of a Lookup will be found automatically where possible.
Span
DimensionalData.Dimensions.Lookups.Span Type
Span <: LookupTraitDefines the type of span used in a Sampling index. These are Regular or Irregular.
DimensionalData.Dimensions.Lookups.Regular Type
Regular <: Span
Regular(step=AutoStep())Points or Intervals that have a fixed, regular step.
DimensionalData.Dimensions.Lookups.Irregular Type
Irregular <: Span
Irregular(bounds::Tuple)
Irregular(lowerbound, upperbound)Points or Intervals that have an Irregular step size. To enable bounds tracking and accurate selectors, the starting bounds are provided as a 2 tuple, or 2 arguments. (nothing, nothing) is acceptable input, the bounds will be guessed from the index, but may be inaccurate.
DimensionalData.Dimensions.Lookups.Explicit Type
Explicit(bounds::AbstractMatrix)Intervals where the span is explicitly listed for every interval.
This uses a matrix where with length 2 columns for each index value, holding the lower and upper bounds for that specific index.
DimensionalData.Dimensions.Lookups.AutoSpan Type
AutoSpan <: Span
AutoSpan()The span will be guessed and replaced in format or set.
Sampling
DimensionalData.Dimensions.Lookups.Sampling Type
Sampling <: LookupTraitIndicates the sampling method used by the index: Points or Intervals.
DimensionalData.Dimensions.Lookups.Points Type
Points <: Sampling
Points()Sampling lookup where single samples at exact points.
These are always plotted at the center of array cells.
DimensionalData.Dimensions.Lookups.Intervals Type
Intervals <: Sampling
Intervals(locus::Position)Sampling specifying that sampled values are the mean (or similar) value over an interval, rather than at one specific point.
Intervals require a locus of Start, Center or End to define the location in the interval that the index values refer to.
Positions
DimensionalData.Dimensions.Lookups.Position Type
Position <: LookupTraitAbstract supertype of types that indicate the locus of index values where they represent Intervals.
These allow for values array cells to align with the Start, Center, or End of values in the lookup index.
This means they can be plotted with correct axis markers, and allows automatic conversions to between formats with different standards (such as NetCDF and GeoTiff).
DimensionalData.Dimensions.Lookups.Center Type
Center <: Position
Center()Used to specify lookup values correspond to the center locus in an interval.
DimensionalData.Dimensions.Lookups.Start Type
Start <: Position
Start()Used to specify lookup values correspond to the start locus of an interval.
DimensionalData.Dimensions.Lookups.Begin Type
Begin <: Position
Begin()Used to specify the begin index of a Dimension axis, as regular begin will not work with named dimensions.
Can be used with : to create a BeginEndRange or BeginEndStepRange.
DimensionalData.Dimensions.Lookups.End Type
End <: Position
End()Used to specify the end index of a Dimension axis, as regular end will not work with named dimensions. Can be used with : to create a BeginEndRange or BeginEndStepRange.
Also used to specify lookup values correspond to the end locus of an interval.
DimensionalData.Dimensions.Lookups.AutoPosition Type
AutoPosition <: Position
AutoPosition()Indicates a interval where the index locus is not yet known. This will be filled with a default value on object construction.
Metadata
DimensionalData.Dimensions.Lookups.AbstractMetadata Type
AbstractMetadata{X,T}Abstract supertype for all metadata wrappers.
Metadata wrappers allow tracking the contents and origin of metadata. This can facilitate conversion between metadata types (for saving a file to a different format) or simply saving data back to the same file type with identical metadata.
Using a wrapper instead of Dict or NamedTuple also lets us pass metadata objects to set without ambiguity about where to put them.
DimensionalData.Dimensions.Lookups.Metadata Type
Metadata <: AbstractMetadata
Metadata{X}(val::Union{Dict,NamedTuple})
Metadata{X}(pairs::Pair...) => Metadata{Dict}
Metadata{X}(; kw...) => Metadata{NamedTuple}General Metadata object. The X type parameter categorises the metadata for method dispatch, if required.
DimensionalData.Dimensions.Lookups.NoMetadata Type
NoMetadata <: AbstractMetadata
NoMetadata()Indicates an object has no metadata. But unlike using nothing, get, keys and haskey will still work on it, get always returning the fallback argument. keys returns () while haskey always returns false.
DimensionalData.Dimensions.Lookups.units Function
units(x) => Union{Nothing,Any}
units(xs:Tuple) => Tuple
unit(A::AbstractDimArray, dims::Tuple) => Tuple
unit(A::AbstractDimArray, dim) => Union{Nothing,Any}Get the units of an array or Dimension, or a tuple of of either.
Units do not have a set field, and may or may not be included in metadata. This method is to facilitate use in labels and plots when units are available, not a guarantee that they will be. If not available, nothing is returned.
Second argument dims can be Dimensions, Dimension types, or Symbols for Dim{Symbol}.