英文:
How to get a @view on a wrapped DataFrame?
问题
我已经封装了一个类似这样的DataFrame，以便编写一些辅助方法。我想要在这个向量上创建一个视图：
series = MySeries{Float64}()
datetimes = @view series[:, :datetime]
function MySeries{T}() where {T}
data = DataFrame(
datetime=DateTime[],
data=T[])
MySeries{T}(data)
end
@inline Base.push!(S::MySeries, dt::DateTime, data) = push!(S.data, [dt, data])
@inline Base.getindex(S::MySeries, i, j) = S.data[i, j]
@inline Base.setindex!(S::MySeries, value, i, j) = S.data[i, j] = value
如果需要进一步的解释或帮助，请随时提问。
英文:
I have wrapped a DataFrame like this in order to write some helper methods. I want to get a view on the vector:
series = MySeries{FLoat64}()
datetimes = @view series[:, :datetime]
function MySeries{T}() where {T}
data = DataFrame(
datetime=DateTime[],
data=T[])
MySeries{T}(data)
end
@inline Base.push!(S::MySeries, dt::DateTime, data) = push!(S.data, [dt, data])
@inline Base.getindex(S::MySeries, i, j) = S.data[i, j]
@inline Base.setindex!(S::MySeries, value, i, j) = S.data[i, j] = value
答案1
得分: 1
这应该可以工作：
Base.view(S::MySeries{T}, i, j) where T = MySeries{T}(Base.view(S.data, i, j))
此外，您可能需要：
Base.getindex(S::MySeries{T}, i, j) where T = MySeries{T}(S.data[i, j])
因为目前您的 `getindex` 函数会解包对象。
最后，您可能希望更仔细地检查 `i` 和 `j` 索引（如果它们是标量选择器，一个维度将被删除，我不确定您的 `MySeries` 对象需要/假设什么）。
英文:
This should work:
Base.view(S::MySeries{T}, i, j) where T = MySeries{T}(Base.view(S.data, i, j))
Also you probably want:
Base.getindex(S::MySeries{T}, i, j) where T = MySeries{T}(S.data[i, j])
as currently your getindex unwraps the object.
Finally you might want to make a more careful checks of i and j indices (as if they are scalar selectors a dimension is dropped and I am not sure what your MySeries object requires/assumes).
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