New python samples. New python function to write grafic files

python/cosmotool/__init__.py

@@ -1,4 +1,5 @@
 from _cosmotool import *
+from grafic import writeGrafic
 from borg import read_borg_vol
 
 

python/cosmotool/grafic.py

@@ -0,0 +1,24 @@
+import struct
+import numpy as np
+
+def writeGrafic(filename, field, BoxSize, scalefac, **cosmo):
+
+    with file(filename, mode="wb") as f:
+        checkPoint = 4*11
+        
+        Nx,Ny,Nz = field.shape
+        delta = BoxSize/Nx
+        bad = 0.0
+        
+        f.write(struct.pack("IIIIffffffffI", checkPoint, 
+                                          Nx, Ny, Nz, 
+                                          delta, 
+                                          bad, bad, bad, 
+                                          scalefac,
+                                          cosmo['omega_M_0'], cosmo['omega_lambda_0'], 100*cosmo['h'], checkPoint))
+        checkPoint = 4*Ny*Nz
+        for i in xrange(Nx):
+            f.write(struct.pack("I", checkPoint))
+            f.write(field[i].astype(np.float32).tostring())
+            f.write(struct.pack("I", checkPoint))
+