pierrelux · October 10, 2019 19:53 · Oct 10, 2019
diff --git a/forest.py b/forest.py
@@ -0,0 +1,34 @@
+import numpy as onp
+
+
+def forest_management(forest_stages=3, r1=4, r2=2, p=0.1):
+    """Forest management example from the MDPToolbox package.
+
+    Chadès, I., Chapron, G., Cros, M.‐J., Garcia, F. and Sabbadin, R. 2014.
+    MDPtoolbox: a multi‐platform toolbox to solve stochastic dynamic programming problems.
+    Ecography 37: 916–920 (ver. 0).
+
+    Args:
+        forest_stages (int, optional): Number of possibles states of the forest: from young to old.
+        Defaults to 3.
+        r1 (int, optional): Payoff for preserving an old forest. Defaults to 4.
+        r2 (int, optional): Payoff for deforesting an old forest. Defaults to 2.
+        p (float, optional): Probability of wildfire. Defaults to 0.1.
+
+    Returns:
+        tuple: (transition, reward, discount)
+    """
+    nactions = 2
+    transition = onp.zeros((nactions, forest_stages, forest_stages))
+    onp.fill_diagonal(transition[0, :, 1:], 1-p)
+    transition[0, :, 0] = p
+    transition[0, -1, -1] = 1-p
+    transition[1, :, 0] = 1
+
+    reward = onp.zeros((forest_stages, nactions))
+    reward[-1, 0] = r1
+    reward[:, 1] = 1
+    reward[0, 1] = 0
+    reward[-1, 1] = r2
+
+    return transition, reward, 0.9
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