SciGraphs · Export a graph
Write the graph out as GraphML, GEXF, Pajek or JSON, export node positions, and generate a statistics report. And know, before you open the file elsewhere, what each route keeps and what it quietly drops.
Mirrors the Export & Tools panel.
Before you begin
Have a graph object active, with whatever attributes you want to carry out already computed in Analysis. Then decide what the file is for. Topology alone, typed numbers for pandas or QGIS, and direction are three different requirements, and no single route in the add-on satisfies all three. Notebook 10 tries eight routes and tabulates what survives each.
1. Set the path and format
In Export Options, set the Path, choose a Format (GraphML, GEXF, JSON or CSV), decide whether to tick Attributes, and press Export Graph. The matching extension is appended if the path lacks it, and an empty path is refused with an error, so the button either writes the file it names or writes nothing.
GEXF, GraphML, Pajek and JSON are also available as quick-format buttons that write straight to that format using the current Path.
CSV ignores the Attributes checkbox. The CSV writer emits an edge list and nothing else, whether the box is ticked or not.
Every GraphML, GEXF and JSON export comes out undirected, whatever the graph was. The writers ask the graph structure whether it is directed, and that structure never carries the flag for anything the add-on builds, while the answer sits on the object itself as is_directed, written and never read. A one-way street network leaves as a two-way one, with no warning and no clue in the file. If direction is the point of the analysis, export through the OSMnx panel instead (step 3).
2. Know what “Attributes” actually carries
Ticking Attributes collects the mesh’s attribute layers and writes them as node attributes. Two consequences are worth checking before the file is analyzed.
No edge attribute leaves through this panel. Edge betweenness, flows and per-edge weights computed onto the mesh simply do not appear in the file. Of the eight routes measured in notebook 10, only the two that read the graph rather than the mesh, GeoPackage and Gephi GraphML, carry an edge attribute at all.
The renderer’s color layers are exported as data. Every color layer the drawing left on the mesh is averaged to a single scalar and written out alongside the real attributes, so a file can arrive with four extra “attributes” that are just the last four figures you rendered. Read the column list before trusting it.
Positions writes the node coordinates to CSV and nothing else. Pair it with a topology export from step 1.
3. When the numbers matter, leave through the OSMnx panel
For an OSMnx-derived network the Import/Export panel has routes this one does not, with their own trade-offs:
- Export → GeoPackage is the only route that returns node and edge attributes as exact float64 values in a file QGIS opens with no repair. Its cost is rows: it is written undirected under OSMnx’s default, which the wrapper does not expose, so a two-way street collapses to a single row (363 of 375 segments in the measured case) and any per-direction quantity loses a value.
- Export → GraphML (Gephi) keeps every node and edge attribute and types none of them: every attribute becomes a string. Right for Gephi, wrong for pandas, where
"0.257"sorts and compares as text. - Save GraphML is the only route that keeps all 375 directed segments, the graph metadata and the values. Reading one back through Load GraphML returns the numbers as strings, because no dtypes are declared on the way in; the values were never lost, only their types.
Notebook 10’s table sets all eight routes side by side and is the fastest way to pick one.
Save GraphML does not refuse an empty path. Unlike Export Graph, it appends the extension to nothing and writes a file literally named .graphml into whatever directory Blender was launched from, then reports success and names it. No glob matches that name and no .gitignore anticipates it. Set the path before pressing the button.
4. Generate a statistics report
In Utilities, tick Power Law Fit to have the degree distribution fitted, and press Generate Report for a text summary of the graph’s metrics. It records what the graph was at export time, which is what makes a mismatch downstream diagnosable.
Next steps
Record the steps that produced the file with Reproducibility, so the graph and the figure can be rebuilt from the pipeline rather than from memory.