mean-based and stacked spatial cross-sectional embeddings in spEDM

[SpatLyu]

This discussion introduces two approaches for constructing spatial cross-sectional embeddings within the spEDM package.

• Mean-based embeddings aggregate neighborhood information by taking the mean of neighbor values at each lag order, producing a compact 2D vector.

• Stacked embeddings, in contrast, preserve the original neighbor values for each lag order and concatenate them to form a 3D vector.