Start file

diff --git a/read_slh_l2.py b/read_slh_l2.py
new file mode 100644 (file)
index 0000000..0cf749a
--- /dev/null
+++ b/read_slh_l2.py
@@ -0,0 +1,181 @@
+# -*- coding: utf-8 -*-
+# MIT License (c) 2017 Ethan Nelson
+
+import struct
+import numpy as np
+import gzip
+
+msg = "File can't be opened. Check its path and extension: %s"
+gz_msg = "File not zipped or can't be opened. Check its path and extension: %s"
+req_msg = "The %s is required to read this file type."
+
+
+def _file_handler(filename):
+    """
+    Handles opening file and exception
+    """
+    if filename[-2:] == 'gz':
+        try:
+            f = gzip.open(filename, 'rb')
+        except:
+            raise Exception(gz_msg % (filename,))
+    else:
+        try:
+            f = open(filename, 'rb')
+        except:
+            raise Exception(msg % (filename,))
+
+    return f
+
+
+def read_gridded(lh_filename=None, q1r_filename=None):
+    """
+    Reads gridded level 2 SLH files.
+
+    Currently, no scaling is done.
+    """
+
+    prodshape = [19, 148, 720]
+    countshape = [148, 720]
+
+    prodsize = 720 * 148 * 19
+    countsize = 720 * 148
+
+    readprodsize = prodsize * 2
+    readcountsize = countsize * 2
+
+    prodstruct = "<" + ('h' * prodsize)
+    countstruct = "<" + ('h' * countsize)
+
+    data = {}
+
+    if lh_filename is not None:
+        f = _file_handler(lh_filename)
+        f.seek(0)
+
+        data['convLHMean'] = f.read(readprodsize)
+        data['convPix'] = f.read(readcountsize)
+        data['stratLHMean'] = f.read(readprodsize)
+        data['stratPix'] = f.read(readcountsize)
+        data['allPix'] = f.read(readcountsize)
+
+        f.close()
+
+    if q1r_filename is not None:
+        f = _file_handler(q1r_filename)
+        f.seek(0)
+        data['convQ1RMean'] = f.read(readprodsize)
+        data['convPix'] = f.read(readcountsize)
+        data['stratQ1RMean'] = f.read(readprodsize)
+        data['stratPix'] = f.read(readcountsize)
+        data['allPix'] = f.read(readcountsize)
+
+        f.close()
+
+    for product in data:
+        if 'Pix' in product:
+            data[product] = struct.unpack(countstruct, data[product])
+            data[product] = np.reshape(data[product], countshape)
+        else:
+            data[product] = struct.unpack(prodstruct, data[product])
+            data[product] = np.reshape(data[product], prodshape)
+
+    return data
+
+
+def read_nongridded(geo_filename=None, dat_filename=None):
+    """
+    Reads non-gridded level 2 SLH files.
+
+    Currently, no scaling is done.
+    """
+
+    if geo_filename is not None:
+        f = _file_handler(geo_filename)
+    else:
+        raise Exception(req_msg % ("geo file",))
+    f.seek(0)
+    geo_data = f.read()
+    f.close()
+
+    nscans = len(geo_data) / 396
+
+    geoshape = [nscans, 49]
+    timeshape = [nscans]
+
+    geosize = 49
+    timesize = 1
+
+    # Non-gridded files are written by scan, so we read one scan at a time
+    readgeosize = geosize * 4
+    readtimesize = timesize * 4
+    onescansize = readgeosize * 2 + readtimesize
+
+    timestruct = "<" + ('f' * timesize * nscans)
+    geostruct = "<" + ('f' * geosize * nscans)
+
+    geovars = ['Scantime', 'Lat', 'Lon']
+
+    data = {}
+
+    for var in geovars:
+        data[var] = ''
+
+    for scan in range(nscans):
+        data['Scantime'] += geo_data[(onescansize*scan):
+                                     (onescansize*scan)+readtimesize]
+        data['Lat'] += geo_data[(onescansize*scan)+readtimesize:
+                                (onescansize*scan)+readtimesize+readgeosize]
+        data['Lon'] += geo_data[(onescansize*scan)+readtimesize+readgeosize:
+                                onescansize*(scan+1)]
+
+    for var in geovars:
+        if var == 'Scantime':
+            data[var] = struct.unpack(timestruct, data[var])
+            data[var] = np.reshape(data[var], timeshape)
+        else:
+            data[var] = struct.unpack(geostruct, data[var])
+            data[var] = np.reshape(data[var], geoshape)
+    data['nscans'] = nscans
+
+    del geo_data, timestruct, geostruct
+
+    if dat_filename is not None:
+        f = _file_handler(dat_filename)
+        f.seek(0)
+
+        prodshape = [nscans, 80, 49]
+        countshape = [nscans, 49]
+
+        # Non-gridded files are written by scan, so we read one scan at a time
+        prodsize = 80 * 49
+        countsize = 49
+
+        readprodsize = prodsize * 2
+        readcountsize = countsize * 2
+
+        prodstruct = "<" + ('h' * prodsize * nscans)
+        countstruct = "<" + ('h' * countsize * nscans)
+
+        datvars = ['lh', 'q1r', 'rtype', 'ltop', 'lmelt', 'lsfc', 'rmelt',
+                   'rsfc', 'rtype2a25', 'method']
+
+        for var in datvars:
+            data[var] = ''
+
+        for i in range(nscans):
+            data['lh'] += f.read(readprodsize)
+            data['q1r'] += f.read(readprodsize)
+            for var in datvars[2:]:
+                data[var] += f.read(readcountsize)
+        f.close()
+
+        for var in datvars:
+            if var in ['lh', 'q1r']:
+                data[var] = struct.unpack(prodstruct, data[var])
+                data[var] = np.reshape(data[var], prodshape)
+            else:
+                data[var] = struct.unpack(countstruct, data[var])
+                data[var] = np.reshape(data[var], countshape)
+
+    return data