hi Felipe -- note you don't have to use the builder classes when you have the exact memory layout already, you can wrap you rmemory in arrow::Buffer and construct the arrays directly.
I think it would be useful to add APIs for appending to builders with a bitmap. We don't have them now, though. This would be a useful contribution to the project. - Wes On Fri, Mar 22, 2019 at 10:26 AM Felipe Aramburu <fel...@blazingdb.com> wrote: > > Is there a way to use a builder to be able to provide a bit per value LSB > as is described in the documentation? I have this already and it seems > silly to convert it to something else so that arrow can then make it the > same format as what I had to begin with. I know there is the ArrayData > class that has a make function that seems to allow me to do this but I am > trying to do things as the documentation suggest which I assumed was the > preferred method of doing this. > > > > On Fri, Mar 22, 2019 at 8:13 AM Francois Saint-Jacques < > fsaintjacq...@gmail.com> wrote: > > > Actually, this specific method seems to use a byte per value as you > > questioned. I think it's worth adding documentation and an explicit warning > > if it confused me. I'll let bkietz chime in to comment on the usage. > > > > François > > > > On Fri, Mar 22, 2019 at 10:57 AM Francois Saint-Jacques < > > fsaintjacq...@gmail.com> wrote: > > > > > Hello Felipe, > > > > > > it's a bit per value as per memory layout documentation. > > > > > > François > > > > > > > > > > > > On Fri, Mar 22, 2019 at 10:48 AM Felipe Aramburu <fel...@blazingdb.com> > > > wrote: > > > > > >> In the builder base class I see this api > > >> > > >> > > >> > > https://github.com/apache/arrow/blob/ad1697e5d25eeaff5630421f55b0120f45cf0ce1/cpp/src/arrow/array/builder_base.h#L149 > > >> > > >> // Vector append. Treat each zero byte as a nullzero. If valid_bytes > > >> is > > >> null > > >> // assume all of length bits are valid. > > >> void UnsafeAppendToBitmap(const uint8_t* valid_bytes, int64_t > > length) > > >> > > >> Is valid_bytes an allocation of size (int8_t) * length, using an entire > > >> byte to indicate validity for each element in the array or is this a > > null > > >> bitmask where in each byte in valid_bytes encodes 8 values, one per bit? > > >> > > >> If this is using a byte per value is there an approved way of using a > > >> builder to initialize an array using the memory layout described here > > >> https://arrow.apache.org/docs/memory_layout.html#null-bitmaps? > > >> > > > > >
