Added support for 4 polarizers system

graph.py

@@ -0,0 +1,48 @@
+import networkx as nx
+
+from solpolpy.polarizers import npol_to_mzp, bpb_to_mzp, mzp_to_bpb, \
+    bpb_to_btbr, btbr_to_bpb, mzp_to_stokes, stokes_to_mzp, \
+    mzp_to_bp3, bp3_to_mzp, btbr_to_mzp, bp3_to_bthp, btbr_to_npol, \
+    fourpol_to_stokes
+
+
+transform_graph = nx.DiGraph()
+transform_graph.add_edge("npol", "MZP",
+                         func=npol_to_mzp,
+                         requires_alpha=False)
+transform_graph.add_edge("MZP", "BpB",
+                         func=mzp_to_bpb,
+                         requires_alpha=True)
+transform_graph.add_edge("BpB", "MZP",
+                         func=bpb_to_mzp,
+                         requires_alpha=True)
+transform_graph.add_edge("BpB", "BtBr",
+                         func=bpb_to_btbr,
+                         requires_alpha=False)
+transform_graph.add_edge("BtBr", "BpB",
+                         func=btbr_to_bpb,
+                         requires_alpha=False)
+transform_graph.add_edge("MZP", "Stokes",
+                         func=mzp_to_stokes,
+                         requires_alpha=False)
+transform_graph.add_edge("Stokes", "MZP",
+                         func=stokes_to_mzp,
+                         requires_alpha=False)
+transform_graph.add_edge("MZP", "Bp3",
+                         func=mzp_to_bp3,
+                         requires_alpha=True)
+transform_graph.add_edge("Bp3", "MZP",
+                         func=bp3_to_mzp,
+                         requires_alpha=True)
+transform_graph.add_edge("BtBr", "MZP",
+                         func=btbr_to_mzp,
+                         requires_alpha=True)
+transform_graph.add_edge("Bp3", "Bthp",
+                         func=bp3_to_bthp,
+                         requires_alpha=True)
+transform_graph.add_edge("BtBr", "npol",
+                         func=btbr_to_npol,
+                         requires_alpha=True)
+transform_graph.add_edge("fourpol", "Stokes",
+                         func=fourpol_to_stokes,
+                         requires_alpha=False)