In 0.4, the views are a revamp of SubArray. So if NamedArrays already interacts well with SubArrays, you're basically set.
FYI the implementation in 0.4 is largely backwards-compatible, but there are some important differences. If you need to dig into the internal implementation of SubArrays, you can find documentation on the changes for 0.4 here: http://docs.julialang.org/en/latest/devdocs/subarrays/ --Tim On Friday, December 05, 2014 04:18:08 AM David van Leeuwen wrote: > Hi, > > On Friday, December 5, 2014 8:47:22 AM UTC+1, Ján Dolinský wrote: > > Hi, > > > > I am exploring DataFrames and NamedArrays packages and I would like to ask > > whether their are suitable for heavier computations and whether I can use > > them directly in BLAS calls (e.g. gemv() etc.). In addition, is it > > possible > > to create views of e.g. DataFrames or NamedArrays ? > > > > I can only speak for NamedArrays. On the one hand the deployment of BLAS > > should be transparant and the use of NamedArray vs Array not lead to much > degradation in performance. E.g., "a * b" with `a` and `b` a NamedArray, > effectively calls "a.array * b.array" which Base implements with > BLAS.gemm(). There is just a little overhead of filling in sensible names > in the result---so if you have small matrices in an inner loop, you're > going to get hurt. > > On the other hand, I am not sure how much of the Julia BLAS cleverness is > retained in NamedArrays---but the intention of the package is that it is > completely transparent, and if you notice bad performance for a particular > situation then you should file an issue (or make a PR:-). Individual > element indexing of a NamedArray with integers is just a little bit slower > than that of an Array. Indexing by name is quite a bit slower---you may > try a different Associative than the standard Dict. > > Incidentally, I've been toying with the idea of NamedArrays `*` check on > consistency of index and dimension names, but my guess is that people would > find such a thing annoying. > > ArrayViews are currently not aware of NameArrays. I believe the views are > going to be part ov julia-0.4, so then it would be a task for NamedArray to > implement views of NamedArrays I gather. > > Cheers, > > ---david > > > Thanks, > > Jan
