csp calculation - fitness function

2 files changed, 70 insertions, 3 deletions

diff --git a/README.rst b/README.rst
index c0d4b7b..ceb34d4 100644
--- a/README.rst
+++ b/README.rst
@@ -1,9 +1,9 @@
-optcut
-======
+opcut
+=====
 
 `https://opcut.herokuapp.com/`
 
-`optcut` is cutting stock problem optimizer
+`opcut` is cutting stock problem optimizer
 (`https://en.wikipedia.org/wiki/Cutting_stock_problem`) utilizing multiple
 panels and guillotine cuts (end-to-end cuts). This project includes multiple
 back-end optimizer implementations and single-page web application front-end.
diff --git a/src_py/opcut/csp.py b/src_py/opcut/csp.py
new file mode 100644
index 0000000..da8906a
--- /dev/null
+++ b/src_py/opcut/csp.py
@@ -0,0 +1,67 @@
+import collections
+import enum
+
+
+InputPanel = collections.namedtuple('InputPanel', ['width', 'height', 'label'])
+InputItem = collections.namedtuple('InputItem', ['width', 'height', 'label',
+                                                 'rotate'])
+OutputPanel = collections.namedtuple('OutputPanel', ['width', 'height',
+                                                     'label', 'items'])
+OutputItem = collections.namedtuple('OutputItem', ['width', 'height', 'label',
+                                                   'x', 'y'])
+
+Method = enum.Enum('Method', ['FORWARD_GREEDY'])
+
+
+def calculate(panels, items, cut_width, method):
+    """Calculate cutting stock problem
+
+    Args:
+        panels (List[InputPanel]): input panels
+        items (List[InputItem]): input items
+        cut_width (float): cut width
+        method (Method): calculation method
+
+    Returns:
+        List[OutputPanel]
+
+    """
+    return {
+        Method.FORWARD_GREEDY: _calculate_forward_greedy
+    }[method](panels, items)
+
+
+def _calculate_forward_greedy(panels, items):
+    pass
+
+
+_Part = collections.namedtuple('_Part', ['panel', 'width', 'height', 'x', 'y'])
+_State = collections.namedtuple('_State', ['inputs', 'outputs'])
+_fitness_K = 0.03
+
+
+def _fitness(state):
+    panel_states = {}
+    for i in state.inputs:
+        if i.panel not in panel_states:
+            panel_states[i.panel] = _State([i], [])
+        else:
+            panel_states[i.panel].inputs.append(i)
+    for i in state.outputs:
+        if i.panel not in panel_states:
+            panel_states[i.panel] = _State([], [i])
+        else:
+            panel_states[i.panel].outputs.append(i)
+
+    total_area = sum(i.width * i.height for i in panel_states.keys())
+    result = 0
+    for panel, panel_state in panel_states.items():
+        result += (panel.width * panel.height -
+                   sum(i.width * i.height
+                       for i in panel_state.outputs)) / total_area
+        result -= (_fitness_K *
+                   min(i.width * i.height for i in panel_state.outputs,
+                       default=0) *
+                   max(i.width * i.height for i in panel_state.inputs,
+                       default=0)) / (total_area * total_area)
+    return result