Lists information about an element of a topology.
(tpm_elemget tpm_id elem_id)
Returns a list of dotted pairs or nil.
| tpm_id | Topology ID (real) |
| elem_id | Element ID (tpm_id) returned by tpm_elemid |
For each dotted pair in the list that is returned, the first value is an integer code for the information type, and the second value is the information. The list format depends on the element type: node, link, or polygon.
| Type | Information |
|---|---|
| 0 | Persistent topology ID (real). |
| -1 | Element type code (integer). With node lists, always 1, meaning node element. |
| -2 | Entity name of the node object (real). |
| 10 | Coordinates of the node object (point). |
| 40 | Node resistance (real). Relevant only for nodes belonging to network or polygon topologies. |
| Type | Information |
|---|---|
| 0 | Persistent topology ID (real). |
| -1 | Element type (integer). With link lists, always 2, meaning link element. |
| -2 | Entity name of the link object (real). |
| 1 | Topology ID of start node (real). |
| 2 | Topology ID of end node (real). |
| 3 | Topology ID of left polygon (real). Relevant only if the link belongs to a polygon topology. Links in a polygon topology can belong to two adjacent polygons, one on the left, and one one the right. |
| 4 | Topology ID of right polygon that shares this link (real). Relevant only if the link belongs to a polygon topology. |
| 40 | Forward resistance of the link (real). |
| 41 | Reverse resistance of the link (real). |
| 70 | Link direction (integer): -1, 0, or 1, where -1 = Reverse, 0 = Bidirectional, and 1 = Forward. |
| Type | Information |
|---|---|
| 0 | Persistent topology ID (real). |
| -1 | Element type (integer). With polygon lists, always 3, meaning polygon element. |
| -2 | Entity name of the polygon centroid (real). |
| 10 | Coordinates of the polygon centroid (point). |
| 50 | Perimeter of the polygon (real). |
| 51 | Area of the polygon (real). |
When a topology is built, it is given a set of object data fields. Their purpose is to contain the information listed in the preceding tables.