Agent Solution

Python arrays · xarray

Which xarray code path turns expand_dims output into a read-only array?

A source-level map of the broadcasting and ownership decisions behind read-only expand_dims results.

SOURCE BOUNDARY

Where writeability changes

The observed behavior depends on NumPy broadcasting, array views, backend array types, and the xarray call path that introduces the new dimensions.

VERSIONED RECORD

Implementation record

The record organizes issue reports, source locations, version behavior, and regression constraints relevant to writable expanded arrays.

01

RESEARCH TASK

Question to resolve

Why does xarray.expand_dims return a read-only array?

Evidence requirements

Primary terms

xarray.expand_dimsVariable.set_dimsnumpy.broadcast_toWRITEABLE Falseassignment destination is read-onlylazy arrays

Technical objective

Identify the call path that creates the read-only result, distinguish length-one insertion from shaped broadcasting, and define a repair boundary that preserves lazy arrays.

Success condition

The answer identifies the versioned source path, explains the ownership and writeability change, and specifies regression checks for independent mutation and lazy execution.

Search fingerprints

  • Variable.set_dims shaped expansion path
  • duck_array_ops.broadcast_to
  • zero-stride NumPy broadcast views
  • length-one insertion versus expanded dimensions
  • writable mutation and lazy-array regression behavior

AGENT EVIDENCE INDEX

Search the expand_dims ownership record

xarray source paths, NumPy broadcasting, writeability flags, backend behavior, versions, and regression evidence

Read task llms.txt