Squashed commit of the following:

commit 91c579a7f4accb79be020c6cc841973def934ace
Author: Michael Hirsch, Ph.D <[email protected]>
Date:   Thu Jul 26 01:30:05 2018 -0400

    functionalize, header function"

commit df2f3297e2b355aa567dcd781fab9bd97127c3ff
Author: Michael Hirsch, Ph.D <[email protected]>
Date:   Wed Jul 25 23:54:12 2018 -0400

    improve test coverage

README.md

@@ -77,6 +77,12 @@ only certain fields are valid for particular satellite systems.
 Not every receiver receives every type of GNSS system.
 Most Android devices in the Americas receive at least GPS and GLONASS.
 
+#### get OBS header
+To get a `dict()` of the RINEX file header:
+```python
+hdr = gr.rinexheader('myfile.rnx')
+```
+
 #### Index OBS data
 
 assume the OBS data from a file is loaded in variable `obs`.

georinex/__init__.py

@@ -1,12 +1,12 @@
 from pathlib import Path
 import logging
 import xarray
-from typing import Union, Tuple
+from typing import Union, Tuple, Dict, Any
 from datetime import datetime
 #
-from .io import opener
-from .rinex2 import rinexnav2, _scan2
-from .rinex3 import rinexnav3, _scan3
+from .io import rinexinfo
+from .rinex2 import rinexnav2, _scan2, obsheader2, navheader2
+from .rinex3 import rinexnav3, _scan3, obsheader3, navheader3
 
 # for NetCDF compression. too high slows down with little space savings.
 COMPLVL = 1
@@ -23,34 +23,19 @@ def readrinex(rinexfn: Path, outfn: Path=None,
     obs = None
     rinexfn = Path(rinexfn).expanduser()
 # %% detect type of Rinex file
-    if rinexfn.suffix in ('.gz', '.zip'):
-        fnl = rinexfn.stem.lower()
-    else:
-        fnl = rinexfn.name.lower()
+    rtype = rinextype(rinexfn)
 
-    if fnl.endswith('n') or fnl.endswith('n.rnx'):
+    if rtype == 'nav':
         nav = rinexnav(rinexfn, outfn)
-    elif fnl.endswith('o') or fnl.endswith('o.rnx'):
+    elif rtype == 'obs':
         obs = rinexobs(rinexfn, outfn, use=use, verbose=verbose)
-    elif fnl.endswith('.crx'):
-        raise NotImplementedError('Hatanaka compressed RINEX is not yet supported')
-    elif rinexfn.suffix.endswith('.nc'):
+    elif rtype == 'nc':
         nav = rinexnav(rinexfn)
         obs = rinexobs(rinexfn)
     else:
         raise ValueError(f"I dont know what type of file you're trying to read: {rinexfn}")
 
     return obs, nav
-
-
-def getRinexVersion(fn: Path) -> float:
-    """verify RINEX version"""
-    fn = Path(fn).expanduser()
-
-    with opener(fn) as f:
-        ver = float(f.readline()[:9])  # yes :9
-
-    return ver
 # %% Navigation file
 
 
@@ -64,13 +49,13 @@ def rinexnav(fn: Path, ofn: Path=None, group: str='NAV') -> xarray.Dataset:
             logging.error(f'Group {group} not found in {fn}')
             return
 
-    ver = getRinexVersion(fn)
-    if int(ver) == 2:
+    info = rinexinfo(fn)
+    if int(info['version']) == 2:
         nav = rinexnav2(fn)
-    elif int(ver) == 3:
+    elif int(info['version']) == 3:
         nav = rinexnav3(fn)
     else:
-        raise ValueError(f'unknown RINEX verion {ver}  {fn}')
+        raise ValueError(f'unknown RINEX  {info}  {fn}')
 
     if ofn:
         ofn = Path(ofn).expanduser()
@@ -101,14 +86,14 @@ def rinexobs(fn: Path, ofn: Path=None,
             logging.error(f'Group {group} not found in {fn}')
             return
 # %% version selection
-    ver = getRinexVersion(fn)
+    info = rinexinfo(fn)
 
-    if int(ver) == 2:
+    if int(info['version']) == 2:
         obs = _scan2(fn, use, tlim=tlim, verbose=verbose)
-    elif int(ver) == 3:
+    elif int(info['version']) == 3:
         obs = _scan3(fn, use, tlim=tlim, verbose=verbose)
     else:
-        raise ValueError(f'unknown RINEX verion {ver}  {fn}')
+        raise ValueError(f'unknown RINEX {info}  {fn}')
 # %% optional output write
     if ofn:
         ofn = Path(ofn).expanduser()
@@ -120,3 +105,51 @@ def rinexobs(fn: Path, ofn: Path=None,
         obs.to_netcdf(ofn, group=group, mode=wmode, encoding=enc)
 
     return obs
+
+
+def rinextype(fn: Path) -> str:
+    if fn.suffix in ('.gz', '.zip'):
+        fnl = fn.stem.lower()
+    else:
+        fnl = fn.name.lower()
+
+    if fnl.endswith('o') or fnl.endswith('o.rnx'):
+        return 'obs'
+    elif fnl.endswith('n') or fnl.endswith('n.rnx'):
+        return 'nav'
+    elif fnl.endswith('.crx'):
+        raise NotImplementedError('Hatanaka compressed RINEX is not yet supported')
+    elif fn.suffix.endswith('.nc'):
+        return 'nc'
+    else:
+        raise ValueError(f"I dont know what type of file you're trying to read: {fn}")
+
+
+def rinexheader(fn: Path) -> Dict[str, Any]:
+    """
+    retrieve RINEX 2/3 header as unparsed dict()
+    """
+    fn = Path(fn).expanduser()
+
+    info = rinexinfo(fn)
+
+    rtype = rinextype(fn)
+
+    if int(info['version']) == 2:
+        if rtype == 'obs':
+            hdr = obsheader2(fn)
+        elif rtype == 'nav':
+            hdr = navheader2(fn)
+        else:
+            raise ValueError(f'Unknown rinex type in {fn}')
+    elif int(info['version']) == 3:
+        if rtype == 'obs':
+            hdr = obsheader3(fn)
+        elif rtype == 'nav':
+            hdr = navheader3(fn)
+        else:
+            raise ValueError(f'Unknown rinex type in {fn}')
+    else:
+        raise ValueError(f'unknown RINEX {info}  {fn}')
+
+    return hdr

georinex/io.py

@@ -3,6 +3,8 @@
 from pathlib import Path
 from contextlib import contextmanager
 import io
+from typing.io import TextIO
+from typing import Union, Dict
 
 
 @contextmanager
@@ -21,9 +23,19 @@ def opener(fn: Path):
     else:
         with fn.open('r') as f:
             yield f
-#
-#        with zipfile.ZipFile(fn, 'r') as z:
-#            flist = z.namelist()
-#            assert len(flist) == 1, f'which filename {flist} do you want from {fn}'
-#            with z.open(flist[0], 'r') as f:
-#                yield f
+
+
+def rinexinfo(f: Union[Path, TextIO]) -> Dict[str, Union[str, float]]:
+    """verify RINEX version"""
+    if isinstance(f, (str, Path)):
+        fn = Path(f).expanduser()
+
+        with opener(fn) as f:
+            return rinexinfo(f)
+
+    line = f.readline()
+
+    info = {'version': float(line[:9]),  # yes :9
+            'filetype': line[20]}
+
+    return info