hs2modis: fix crash in Cris2Modis

ModisSrfCatalog is copied from old/v2-modisfuse/intercal/modis_srf.py

src/intercal/hs2modis.py

 
 import itertools
 import numpy as np
-from intercal.modis_srf import ModisSrfCatalog
+from pyhdf import SD
+from intercal.srf import WavelengthSrf
+from intercal.util import wn2wl
+
+class ModisSrfCatalog(object):
+
+    def __init__(self, srf_path):
+
+        self.srfs = self.read_srfs(srf_path)
+
+    def get(self, band):
+
+        return self.srfs[band]
+
+    def read_srfs(self, srf_path):
+
+        sd = SD.SD(srf_path)
+
+        # work around a weird issue with modis_terra.srf.nc. indexing the
+        # SDS with [:] returns [20 0 0 ...], but doing it this way works
+        # fine. no idea why
+        band = list(sd.select('channel_list'))
+        nu_begin = sd.select('begin_frequency')[:]
+        nu_end = sd.select('end_frequency')[:]
+
+        srfs = {}
+        for band, nu_begin, nu_end in zip(band, nu_begin, nu_end):
+            F = sd.select('channel_%s_response' % band)[:][::-1]
+            lambda_ = wn2wl(np.linspace(nu_begin, nu_end, len(F)))[::-1]
+            srfs[band] = WavelengthSrf(lambda_, F)
+        sd.end()
+
+        return srfs
 
 class Airs2Modis(object):
 
@@ -36,7 +68,7 @@ class Airs2Modis(object):
 #   2. an array with the channel wavenumbers
 #   3. an array with the channel noise equivalent delta temperatures
 #      at 250K
-#   
+#
 def read_airs_chan_data(filename):
 
     # loop through lines in the text file:
@@ -97,4 +129,3 @@ def convert_to_wavelength_based_radiance(nu, rad_nu):
     lambda_ = 10000.0 / nu
     rad_lambda = rad_nu * 1e-7 * nu**2
     return lambda_[::-1], rad_lambda[...,::-1]
-