\Replace kMinFlow with kEpsilon for flow threshold checks in place_on_dag and max_flow functions

Author: networmix

Makefile

@@ -6,8 +6,8 @@
 
 VENV_BIN := $(PWD)/venv/bin
 # Use dynamic (recursive) assignment so a newly created venv is picked up
-# Prefer the python3 on PATH (e.g., set by setup-python)
-PY_FIND := $(shell command -v python3 2>/dev/null || command -v python 2>/dev/null)
+# Prefer explicit versions first (newest to oldest), then python3 on PATH
+PY_FIND := $(shell for v in 3.13 3.12 3.11 3.10; do command -v python$$v >/dev/null 2>&1 && { echo python$$v; exit 0; }; done; command -v python3 2>/dev/null || command -v python 2>/dev/null)
 PYTHON ?= $(if $(wildcard $(VENV_BIN)/python),$(VENV_BIN)/python,$(PY_FIND))
 PIP = $(PYTHON) -m pip
 PYTEST = $(PYTHON) -m pytest
@@ -123,13 +123,13 @@ build:
 
 clean:
 	@echo "🧹 Cleaning build artifacts and cache files..."
-	@rm -rf build/ dist/ *.egg-info/
+	@rm -rf build/ dist/ *.egg-info/ || true
 	@find . -type d -name "__pycache__" -exec rm -rf {} + 2>/dev/null || true
 	@find . -type f -name "*.pyc" -delete 2>/dev/null || true
 	@find . -type f -name "*.pyo" -delete 2>/dev/null || true
-	@rm -f .coverage coverage-*.xml coverage-*.html
-	@rm -rf htmlcov-python
-	@rm -rf Testing CTestTestfile.cmake
+	@rm -f .coverage coverage-*.xml coverage-*.html || true
+	@rm -rf htmlcov-python || true
+	@rm -rf Testing CTestTestfile.cmake || true
 	@echo "✅ Cleanup complete!"
 
 info:

pyproject.toml

@@ -41,6 +41,8 @@ dev = [
     "pre-commit",
     "build",
     "twine",
+    "cmake>=3.23",
+    "ninja",
 ]
 
 [project.urls]

src/flow_state.cpp

@@ -324,15 +324,15 @@ Flow FlowState::place_on_dag(NodeId src, NodeId dst, const PredDAG& dag,
     while (!q.empty()) {
       auto u = q.front(); q.pop();
       double f_in = inflow[static_cast<std::size_t>(u)];
-      if (f_in < kMinFlow) continue;
+      if (f_in < kEpsilon) continue;
       int split = node_split[static_cast<std::size_t>(u)];
       if (split <= 0) continue;
       for (auto gi : succ[static_cast<std::size_t>(u)]) {
         const auto& gr = groups[gi];
         if (gr.eids.empty()) continue;
         // Group share proportional to number of edges (equal per-edge split).
         double push = f_in * (static_cast<double>(gr.eids.size()) / static_cast<double>(split));
-        if (push < kMinFlow) continue;
+        if (push < kEpsilon) continue;
         assigned[gi] += push;
         auto v = static_cast<std::size_t>(gr.from);
         inflow[v] += push;

src/max_flow.cpp

@@ -80,6 +80,7 @@ calc_max_flow(const StrictMultiDiGraph& g, NodeId src, NodeId dst,
 
     Cost path_cost = dist[static_cast<std::size_t>(dst)];
     Flow placed = fs.place_on_dag(src, dst, dag, std::numeric_limits<double>::infinity(), placement);
+
     if (placed < kMinFlow) break;
     total += placed;
     // Merge by exact cost (integer)