Merge pull request dimitri-yatsenko#54 from dimitri-yatsenko/claude/add-diagram-intersection-OV8Wi

Add intersection operator for diagram operations

Author: dimitri-yatsenko

book/30-design/060-diagrams.ipynb

@@ -689,28 +689,7 @@
    "cell_type": "markdown",
    "id": "cell-21",
    "metadata": {},
-   "source": [
-    "# Diagram Operations\n",
-    "\n",
-    "DataJoint provides operators to filter and combine diagrams for exploring large schemas:\n",
-    "\n",
-    "```python\n",
-    "# Show entire schema\n",
-    "dj.Diagram(schema)\n",
-    "\n",
-    "# Show specific tables\n",
-    "dj.Diagram(Table1) + dj.Diagram(Table2)\n",
-    "\n",
-    "# Show table and N levels of upstream dependencies\n",
-    "dj.Diagram(Table) - N\n",
-    "\n",
-    "# Show table and N levels of downstream dependents\n",
-    "dj.Diagram(Table) + N\n",
-    "\n",
-    "# Combine operations\n",
-    "(dj.Diagram(Table1) - 2) + (dj.Diagram(Table2) + 1)\n",
-    "```"
-   ]
+   "source": "# Diagram Operations\n\nDataJoint provides operators to filter and combine diagrams for exploring large schemas:\n\n```python\n# Show entire schema\ndj.Diagram(schema)\n\n# Show specific tables\ndj.Diagram(Table1) + dj.Diagram(Table2)\n\n# Show table and N levels of upstream dependencies\ndj.Diagram(Table) - N\n\n# Show table and N levels of downstream dependents\ndj.Diagram(Table) + N\n\n# Combine operations\n(dj.Diagram(Table1) - 2) + (dj.Diagram(Table2) + 1)\n\n# Intersection: show only common nodes between two diagrams\ndj.Diagram(Table1) * dj.Diagram(Table2)\n```\n\n## Finding Paths Between Tables\n\nThe intersection operator `*` is particularly useful for finding connection paths between two tables in a large schema.\nBy expanding one table downstream and another upstream, then taking the intersection, you reveal only the tables that form the path(s) between them:\n\n```python\n# Find all paths connecting table1 to table2 (where table2 is downstream from table1)\n(dj.Diagram(table1) + 100) * (dj.Diagram(table2) - 100)\n```\n\nThis works because:\n- `dj.Diagram(table1) + 100` includes table1 and up to 100 levels of downstream dependents\n- `dj.Diagram(table2) - 100` includes table2 and up to 100 levels of upstream dependencies\n- The intersection `*` shows only tables that appear in **both** diagrams—the connecting path(s)"
   },
   {
    "cell_type": "code",
@@ -723,6 +702,14 @@
     "dj.Diagram(schema)"
    ]
   },
+  {
+   "cell_type": "code",
+   "id": "tpx88p488y",
+   "source": "# Find the path from Student to Enrollment using intersection\n# Expand Student downstream and Enrollment upstream, then intersect\n(dj.Diagram(Student) + 100) * (dj.Diagram(Enrollment) - 100)",
+   "metadata": {},
+   "execution_count": null,
+   "outputs": []
+  },
   {
    "cell_type": "markdown",
    "id": "cell-23",
@@ -884,4 +871,4 @@
  },
  "nbformat": 4,
  "nbformat_minor": 5
-}
+}