Hi David,
You should look into the visitor facilities provided by Arrow C++, in arrow/visitor_inline.h. I would especially look at two of them: - VisitArrayInline() will call the visitor's overloaded Visit() method with the right array concrete type (for example Int16Array, ListArray...) - Once you know the concrete type (for example Int16Type, which is Int16Array::TypeClass), you can use ArrayDataVisitor<ConcreteType> to iterate over each array element Regards Antoine. Le 10/10/2019 à 17:31, david sherrier a écrit : > Hey all, > > I'm working on a simple serial join implementation and need to be able to > compare data across two columns of the same type. Right now the only way I > have found to do this is too use ArrayData::GetValues<T>(1) and then > iterate over the returned buffer comparing the values. The problem I am > having with this approach is that I need the type in the template meaning > that when I need to add a row to the result table I need to know the type > of each column which would seem like a needlessly large switch statement > comparing on the type id and then returning the type. This also seems to > only work for fixed length types it would appear to be even more > complicated to read string data but I have not tried that yet. Is there an > easier way too do this that I am missing? The second issue I am having is > that comparisons between types that do not inherit from ctypes seem to not > be implemented yet in particular for this use case String type. I would > have expected that since tables have a defined schema with the type known > there would be some sort of iterator to read over column data? > > Thanks, > David Sherrier >
