Add Documentation about reading the time series format.

Author: Christoph Paulik

Diff for: README.rst

@@ -143,3 +143,18 @@ Conversion to time series is performed by the `repurpose package
 or other options see the `repurpose documentation
 <http://repurpose.readthedocs.io/en/latest/>`_ and the code in
 ``ecmwf_models.reshuffle``.
+
+Reading converted time series data
+----------------------------------
+
+For reading the data the ``ecmwf_repurpose`` command produces the class
+``ERAInterimTs`` can be used:
+
+.. code-block:: python
+
+    from ecmwf_models.interface import ERAinterimTs
+    ds = ERAinterimTs(ts_path)
+    # read_ts takes either lon, lat coordinates or a grid point indices.
+    # and returns a pandas.DataFrame
+    ts = ds.read_ts(45, 15)
+

Diff for: ecmwf_models/interface.py

@@ -26,6 +26,7 @@
 Interface to reading ecmwf reanalysis data.
 '''
 import warnings
+import os
 
 try:
     import pygrib
@@ -36,6 +37,12 @@
 from pygeobase.object_base import Image
 import numpy as np
 from datetime import timedelta
+try:
+    from pynetcf.time_series import GriddedNcOrthoMultiTs
+    import pygeogrids
+except ImportError:
+    warnings.warn(
+        "For reading converted time series the pynetcf package is necessary.")
 
 
 class ERAInterimImg(ImageBase):
@@ -160,3 +167,14 @@ def tstamps_for_daterange(self, start_date, end_date):
             timestamps.extend(daily_dates.tolist())
 
         return timestamps
+
+
+class ERAinterimTs(GriddedNcOrthoMultiTs):
+
+    def __init__(self, ts_path, grid_path=None):
+
+        if grid_path is None:
+            grid_path = os.path.join(ts_path, "grid.nc")
+
+        grid = pygeogrids.netcdf.load_grid(grid_path)
+        super(ERAinterimTs, self).__init__(ts_path, grid)

Diff for: tests/test_reshuffle.py

@@ -32,8 +32,7 @@
 import numpy.testing as nptest
 
 from ecmwf_models.reshuffle import main
-import pygeogrids
-from pynetcf.time_series import GriddedNcOrthoMultiTs
+from ecmwf_models.interface import ERAinterimTs
 
 
 def test_reshuffle():
@@ -48,8 +47,7 @@ def test_reshuffle():
     args = [inpath, ts_path, startdate, enddate] + parameters
     main(args)
     assert len(glob.glob(os.path.join(ts_path, "*.nc"))) == 2589
-    grid = pygeogrids.netcdf.load_grid(os.path.join(ts_path, 'grid.nc'))
-    ds = GriddedNcOrthoMultiTs(ts_path, grid)
+    ds = ERAinterimTs(ts_path)
     ts = ds.read_ts(45, 15)
     ts_39_values_should = np.array([0.17183685,  0.17189026,  0.17173004,
                                     0.17175293,  0.17183685, 0.17189026,