[python] Added logger callback

bindings/python/crocoddyl/__init__.py

@@ -50,4 +50,33 @@ class CallbackSolverDisplay(libcrocoddyl_pywrap.CallbackAbstract):
         if (solver.iter + 1) % self.freq:
             return
         dt = solver.models()[0].dt
-        displayTrajectory(self.robotwrapper, solver.xs, dt, self.rate, self.cameraTF)
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+        displayTrajectory(self.robotwrapper, solver.xs, dt, self.rate, self.cameraTF)
+
+
+class CallbackSolverLogger(libcrocoddyl_pywrap.CallbackAbstract):
+    def __init__(self):
+        libcrocoddyl_pywrap.CallbackAbstract.__init__(self)
+        self.steps = []
+        self.iters = []
+        self.costs = []
+        self.control_regs = []
+        self.state_regs = []
+        self.th_stops = []
+        self.gm_stops = []
+        self.xs = []
+        self.us = []
+        self.gaps = []
+
+    def __call__(self, solver):
+        import copy
+        import numpy as np
+        self.xs = copy.copy(solver.xs)
+        self.us = copy.copy(solver.us)
+        self.steps.append(solver.stepLength)
+        self.iters.append(solver.iter)
+        self.costs.append(solver.cost)
+        self.control_regs.append(solver.u_reg)
+        self.state_regs.append(solver.x_reg)
+        self.th_stops.append(solver.stoppingCriteria)
+        self.gm_stops.append(-np.asscalar(solver.expectedImprovement()[1]))
+        self.gaps.append(copy.copy(solver.gaps))
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