Euclidean distances between the 30 policing hotspots of table_8_4, which
determine which hotspots are exposed to a treated neighbor.
A 30 by 30 numeric matrix. Row and column i correspond to
table_8_4$hotspot == i, and the diagonal is zero.
Source
Computed from the hotspot coordinates described under table_8_4.
Built by data-raw/book_tables.R.