Hi
I'm looking for the easiest way to create a lagged variable in a dataframe.
I'm almost there with this:
df = DataFrame(id=repeat([1:3],inner=[3],outer=[1]),time=repeat([1:3],inner
=[1],outer=[3]),y=rand(9))
by(df2, :id , d -> DataFrame(time=d[:,:time],y=d[:,:y],Ly=[0,d[1:end-1,:y
]]))
but of course instead of the 0.0 for the first entry for each id I would
like to have an NA:
by(df, :id , d -> DataFrame(time=d[:,:time],y=d[:,:y],Ly=[NA,d[1:end-1,:y
]]))
but I cant figure out how to pass a valid data type here. thsi says "ERROR:
no method convert(Type{Float64}, NAtype)"
i tried also this
by(df, :id , d -> DataFrame(time=d[:,:time],y=d[:,:y],Ly=@data([NA,d[1:end-1
,:y]])))
but that gives "ERROR: no method DataArray{T,N}(DataArray{Float64,1},
Array{Bool,1})".
