dot export: add xgboost support and documentation

1 files changed, 11 insertions, 0 deletions

diff --git a/doc/model-visual.md b/doc/model-visual.md
index 4f629d1..7830421 100644
--- a/doc/model-visual.md
+++ b/doc/model-visual.md
@@ -5,3 +5,14 @@
 In low- to medium-complexity applications, the simplest way of examining the
 performance models generated by dfatool is textual output: `--show-model=param`.
 This is implemented for most modeling methods.
+
+## Graphical Output via dot(1)
+
+`--export-dot PREFIX` exports the generated performance models for each pair of
+name (state/transition/…) and performance attribute to
+`PREFIX(name)-(attribute).dot`. The dot(1) program is capable of transforming
+those into images. For instance, if feh(1) is available, a visual model is
+accessible via `dot -Tpng filename.dot | feh -`.
+
+In case of regression forests (XGBoost), dfatool exports the individual trees to
+`PREFIX(name)-(attribute).(index).dot`.