Parametric diagram scripts (script = source of truth)

When to use

Drawing a structure figure from scratch (not replicating a bitmap) that you expect to revise: add nodes, recolor, reword, reuse in the next paper. Hand-editing SVG coordinates every revision is painful; with a parametric script you edit the declaration block and re-run. For one-shot figures, hand-svg-structure is fine.

Template

make_fig.py in this folder is the complete pattern (a three-layer fully-connected network figure), three declaration blocks:

COLS      = {...}   # geometry: columns / centers / radii / row ys (or box x,y,w,h)
NODE_TEXT = {...}   # content: per-node text (main letter, subscript, subscript-italic?)
STYLE     = {...}   # style: palette / line widths / font sizes / families, one place
def mesh(): ...     # topology: loops generate edges (fully-connected / zip chains / trees)
def build(): ...    # assemble the SVG string and write to disk

Adding a node = one entry in COLS["ys"] + one line in NODE_TEXT. Recoloring = STYLE. Then python make_fig.py regenerates the SVG; export PNG via the hand-svg-structure export pages.

Craft notes (field lessons)

• Compute connector endpoints from declared constants (centers ± radii) — no scattered magic numbers.
• Arrow markers: markerUnits="userSpaceOnUse" + orient="auto", line end pulled back 1.5–2 px so the tip touches the target edge.
• Converging/fully-connected figures: end all incoming edges at the target's left pole (cx-(r+2), cy) so arrowheads stack into a cluster (radial landing reads as wrong vs. classic references).
• Subscript regime: main letters in italic serif; digit subscripts explicitly upright (tspans inherit italics); letter subscripts italic.
• Chinese layer/section labels in a hei-ti face; in-node math in Times.

Example

examples/fig-mlp.svg/.png — three-layer fully-connected network (x_d —W1→ h_N —W2→ f_C) with hidden-layer band, stacked arrowhead clusters, ellipsis dots; mlp_reference.png is the reference it replicates (accepted by the visual judge on first re-check).