Read in Liam's wavenumber-based VIIRS SRFs

cris2viirs_pre.py

 
+from collections import deque
 import sys
 
 import numpy as np
@@ -16,37 +17,50 @@ def parse_srf_file(filename):
         and weights.
         """
 
-    # create an SRF object with the channel number and arrays
-    # to represent the RSR
+    # this function will return a dict of SRF objects indexed by band
+    srf_info = {}
+
     with open(filename) as f:
-        wn_list, resp_list = [], []
-        for line in f:
-            if line.startswith('#'):
-                continue
-            wl_nm, resp = (float(x) for x in line.split())
-            wn = 1e7 / wl_nm
-            resp /= wn**2
-            wn_list.append(wn)
-            resp_list.append(resp)
-    srf = SRF()
-    srf.channel = filename[17:20]
-    srf.wavenumbers = np.array(wn_list[::-1])
-    srf.weights = np.array(resp_list[::-1])
-
-    return srf
-
-if len(sys.argv) < 2:
-    print 'usage: %s <srf_file> ... <output_filename>' % sys.argv[0]
+
+        # skip header line
+        f.readline()
+
+        # remainder of file contains records that each have the band
+        # number, the number of points in the SRF, the first then last
+        # wavenumber, then the SRF response values
+        tokens = deque(f.read().split())
+        while tokens:
+
+            band = int(tokens.popleft())
+            points = int(tokens.popleft())
+            nu_begin = float(tokens.popleft())
+            nu_end = float(tokens.popleft())
+
+            nu = np.linspace(nu_begin, nu_end, points)
+            F = np.array([float(tokens.popleft()) for i in range(points)])
+
+            srf = SRF()
+            srf.channel = band
+            srf.wavenumbers = nu
+            srf.weights = F
+
+            srf_info[band] = srf
+
+    return srf_info
+
+if len(sys.argv) != 3:
+    print 'usage: %s <srf_file> <output_filename>' % sys.argv[0]
     sys.exit(1)
-srf_filenames = sys.argv[1:-1]
-output_filename = sys.argv[-1]
+srf_filename = sys.argv[1]
+output_filename = sys.argv[2]
 
 # ingest SRF data for the given filenames
-srf_info = [parse_srf_file(srf_filename) for srf_filename in srf_filenames]
+srf_info = parse_srf_file(srf_filename)
+srf_info = [srf_info[band] for band in (13, 15, 16)]
 
 # create an array of the M-band numbers
 # FIXME: we'll need to support I-bands too
-viirs_bands = np.array([int(srf.channel[1:3]) for srf in srf_info], np.int32)
+viirs_bands = np.array([srf.channel for srf in srf_info], np.int32)
 
 # create an array of CrIS wavenumbers
 # FIXME: is this right?