feat(core): Add basic report mechanism

core/nurse_scheduling/preference_types.py

@@ -1,5 +1,7 @@
 from . import utils
 from .context import Context
+from .report import Report
+
 
 def all_requirements_fulfilled(ctx: Context, preference, preference_idx):
     # Hard constraint
@@ -34,16 +36,17 @@ def assign_shifts_evenly(ctx: Context, preference, preference_idx):
 
         # Construct: L2 = actual_n_shifts - target_n_shifts) ** 2
         MAX = max(ctx.n_days - target_n_shifts, target_n_shifts)
-        diff_var_name = f"{unique_var_prefix}_diff"
+        diff_var_name = f"{unique_var_prefix}diff"
         ctx.model_vars[diff_var_name] = diff = ctx.model.NewIntVar(0, MAX, diff_var_name)
         ctx.model.add_abs_equality(diff, actual_n_shifts - target_n_shifts)
-        L2_var_name = f"{unique_var_prefix}_L2"
+        L2_var_name = f"{unique_var_prefix}L2"
         ctx.model_vars[L2_var_name] = L2 = ctx.model.NewIntVar(0, MAX**2, L2_var_name)
         ctx.model.AddMultiplicationEquality(L2, diff, diff)
 
         # Add the objective
         weight = -1000000
         ctx.objective += weight * L2
+        ctx.reports.append(Report(f"assign_shifts_evenly_L2_p_{p}", L2, lambda x: x == 0))
 
 def shift_request(ctx: Context, preference, preference_idx):
     # Soft constraint
@@ -60,6 +63,7 @@ def shift_request(ctx: Context, preference, preference_idx):
         # Add the objective
         weight = 1
         ctx.objective += weight * ctx.shifts[(d, r, p)]
+        ctx.reports.append(Report(f"shift_request_p_{p}_d_{d}_r_{r}", ctx.shifts[(d, r, p)], lambda x: x == 1))
 
 PREFERENCE_TYPES_TO_FUNC = {
     "all requirements fulfilled": all_requirements_fulfilled,

core/nurse_scheduling/report.py

@@ -0,0 +1,7 @@
+from dataclasses import dataclass
+
+@dataclass
+class Report:
+    description: str
+    variable: 'typing.Any'
+    skip_condition: 'typing.Any' = lambda x: False

core/nurse_scheduling/scheduler.py

@@ -1,12 +1,14 @@
 import itertools
 import logging
 from datetime import timedelta
+from typing import List
 
 from ortools.sat.python import cp_model
 
 from . import export, preference_types
 from .context import Context
 from .dataloader import load_data
+from .report import Report
 
 
 def schedule(filepath: str, validate=True, deterministic=False):
@@ -31,6 +33,7 @@ def schedule(filepath: str, validate=True, deterministic=False):
     logging.info("Initializing solver model...")
     ctx.model = cp_model.CpModel()
     ctx.model_vars = {}
+    ctx.reports: List[Report] = []
     ctx.shifts = {}
     """A set of indicator variables that are 1 if and only if
     a person (p) is assigned to a shift (d, r)."""
@@ -125,10 +128,15 @@ def on_solution_callback(self):
     logging.info(f"  - conflicts: {solver.NumConflicts()}")
     logging.info(f"  - branches : {solver.NumBranches()}")
     logging.info(f"  - wall time: {solver.WallTime()}s")
-
     logging.info("Variables:")
     for k, v in ctx.model_vars.items():
         logging.info(f"  - {k}: {solver.Value(v)}")
+    logging.info("Reports:")
+    for report in ctx.reports:
+        val = solver.Value(report.variable)
+        if report.skip_condition(val):
+            continue
+        logging.info(f"  - {report.description}: {val}")
 
     logging.info(f"Done.")