Hi Rares, ArrayData::GetMutableValues would return a nullptr if the requested buffer is not available. https://github.com/apache/arrow/blob/557a7c63d49aa04508564517c77c71f3657d19ff/cpp/src/arrow/array/data.h#L199
What does nAtts stand for? could it be that it is OOB? On Fri, Jul 30, 2021 at 12:55 PM Rares Vernica <rvern...@gmail.com> wrote: > Hello, > > I have a RecordBatch that I read from an IPC file. I need to run a > cumulative sum on one of the int64 arrays in the batch. I tried to do: > > std::shared_ptr<arrow::ArrayData> pos_data = batch->column_data(nAtts); > auto pos_values = pos_data->GetMutableValues<int64_t>(1); > for (auto i = 1; i < pos_data->length; i++) > pos_values[i] += pos_values[i - 1]; > > but GetMutableValues returns NULL. If I use GetValue, it works fine, but I > can't run the cumulative sum on the returned pointer since it is read-only. > I tried creating a copy of ArryaData like so: > > std::shared_ptr<arrow::ArrayData> pos_data = > batch->column_data(nAtts)->Copy(); > > but it did not help. All this data is in CPU buffers so I'm not sure what > is the problem. What is the best way to mutate or copy & mutate it? > > Thanks! > Rares > -- Niranda Perera https://niranda.dev/ @n1r44 <https://twitter.com/N1R44>
