mapobs(f, data; batched=:auto)

Lazily map f over the observations in a data container data. Returns a new data container mdata that can be indexed and has a length. Indexing triggers the transformation f.

The batched keyword argument controls the behavior of mdata[idx] and mdata[idxs] where idx is an integer and idxs is a vector of integers:

• batched=:auto (default). Let f handle the two cases. Calls f(getobs(data, idx)) and f(getobs(data, idxs)).

• batched=:never. The function f is always called on a single observation. Calls f(getobs(data, idx)) and [f(getobs(data, idx)) for idx in idxs].

• batched=:always. The function f is always called on a batch of observations. Calls getobs(f(getobs(data, [idx])), 1) and f(getobs(data, idxs)).

Examples

			
			julia> data = (a=[1,2,3], b=[1,2,3]);

julia> mdata = mapobs(data) do x
         (c = x.a .+ x.b,  d = x.a .- x.b)
       end
mapobs(#25, (a = [1, 2, 3], b = [1, 2, 3]); batched=:auto))

julia> mdata[1]
(c = 2, d = 0)

julia> mdata[1:2]
(c = [2, 4], d = [0, 0])

			mapobs(fs, data)

Lazily map each function in tuple fs over the observations in data container data. Returns a tuple of transformed data containers.

			mapobs(namedfs::NamedTuple, data)

Map a NamedTuple of functions over data, turning it into a data container of NamedTuples. Field syntax can be used to select a column of the resulting data container.

			
			
			
			data
			 
			=
			
			 
			1
			:
			10
			

			
			nameddata
			 
			=
			 
			

			mapobs
			(
			
			(
			
			x
			 
			=
			 
			sqrt
			,
			 
			
			y
			 
			=
			 
			log
			)
			,
			 
			data
			)
			

			
			

	
			getobs
			(
			nameddata
			,
			 
			10
			)
			 
			==
			 
			
			(
			
			x
			 
			=
			 
			
			sqrt
			(
			10
			)
			,
			 
			
			y
			 
			=
			 
			
			log
			(
			10
			)
			)
			

			
			

	
			getobs
			(
			
			nameddata
			.
			
			x
			,
			 
			10
			)
			 
			==
			 
			
			sqrt
			(
			10
			)