wire-cell-arrow

Arrow schema definitions and converters for Wire-Cell Toolkit (WCT) data types.

This package provides:

• Apache Arrow schemas for WCT IData types (IFrame, ITrace, IDepo, IDepoSet, ITensor, ITensorSet)
• Converters from WCT IData objects to Arrow Table/RecordBatch objects
• ArrowXxx concrete classes implementing WCT interfaces as lazy facades over Arrow objects
• Collection operators for decomposing and reassembling Arrow container types

See docs/design.md for schema rationale, docs/api.md for usage examples, docs/fidelity.md for the per-type round-trip fidelity notes (what each converter preserves, normalizes, or drops), and docs/schema-versioning.md for the semantic schema version, compatibility policy, and schema registry.

Prerequisites

• Wire-Cell Toolkit (WCT)
• Apache Arrow (arrow-cpp via Spack)
• C++23 compiler (GCC 15+ via Spack view)

Build

The default CMake preset pins the Spack GCC 15 toolchain via $CC/$CXX (the Debian system GCC 12 lacks the C++23 features the WCT/phlex headers need). Set them from the Spack store — the umbrella .envrc does this:

export CC="$(spack -e wcph location -i gcc@15)/bin/gcc"
export CXX="$(spack -e wcph location -i gcc@15)/bin/g++"

cmake --preset default -S source/wire-cell-arrow -B builds/wire-cell-arrow
cmake --build builds/wire-cell-arrow
ctest --test-dir builds/wire-cell-arrow

Components

• wire_cell_arrow/Converters.{hpp,cpp} — schema factories (trace_schema, depo_schema, tensor_schema, …) and to_arrow(...) converters (WCT → Arrow).
• wire_cell_arrow/Arrow{Trace,Depo,Tensor,Frame,DepoSet,TensorSet}.{hpp,cpp} — lazy facades implementing the WCT interfaces over Arrow objects (Arrow → WCT).
• wire_cell_arrow/Ops.{hpp,cpp} — collection operators (decompose/reassemble).

The C++ namespace is WireCell::Arrow (capital A, so an unqualified arrow:: refers to Apache Arrow).