feat & refac: added conversion functions and removed redundant code

pyicon/pyicon_calc_xr.py

-print('sys glob os')
-import sys
-import glob, os
-#import datetime
 print('numpy')
 import numpy as np
-print('netcdf')
-from netCDF4 import Dataset, num2date
-#print('ipdb')
-#from ipdb import set_trace as mybreak  
 print('xarray')
 import xarray as xr
 print('Done modules calc.')
 
 def convert_tgrid_data(ds_tg):
-
     """ Convert xarray grid file to grid file compatible with pyicon function.
 
-Open classical ICON grid file by:
-ds_tg = xr.open_dataset(fpath_tg, chunks=dict())
+    Open classical ICON grid file by:
+    ds_tg = xr.open_dataset(fpath_tg, chunks=dict())
 
-Then convert by:
-ds_IcD = pyic.convert_tgrid_data(ds_tg)
+    Then convert by:
+    ds_IcD = pyic.convert_tgrid_data(ds_tg)
 
-ds_tg and ds_IcD are both lazy xarray data sets containing dask arrays.
+    ds_tg and ds_IcD are both lazy xarray data sets containing dask arrays.
     """
     ds_IcD = xr.Dataset()
     
@@ -116,6 +107,50 @@ ds_tg and ds_IcD are both lazy xarray data sets containing dask arrays.
 
     return ds_IcD
 
+
+def convert_fxgrid_data(ds_fxg):
+    # Here we assume the name mapping is alwys in the same order
+    # This may not necessarily be the case so proceed with caution
+    name_mapping = {
+        "ncells": "cell",
+        "ncells_2": "edge",
+        "ncells_3": "vertex",
+        "vertices": "nv",
+        "vertices_2": "nc",
+        "vertices_3": "ne"
+        }
+
+    for key in name_mapping:
+        if key in ds_fxg.dims:
+            ds_fxg = ds_fxg.rename_dims({key: name_mapping[key]})
+
+    return ds_fxg
+    
+
+def convert_data(ds_data):
+    # For some reason edge points sometimes have an nc of 4 rather than 2
+    # So proceed with caution. We use the value nc, nv or ne to ascertain
+    # What type of point something is.
+    name_mapping = {
+        2: ("nc", "edge"),
+        3: ("nv", "cell"),
+        4: ("nc", "edge"),
+        6: ("ne", "vertex")
+    }
+
+    for key in ds_data.dims:
+        if key.startswith("vertices"):
+            vertex_suffix = key[8:]
+            
+            vertices = ds_data.dims[key]
+            
+            ds_data = ds_data.rename_dims({
+                key: name_mapping[vertices][0],
+                "ncells" + vertex_suffix: name_mapping[vertices][1]
+                                           })
+    return ds_data
+
+
 def print_verbose(verbose=1, message="", verbose_stage=1):
   if verbose>=verbose_stage:
     print(message)
@@ -345,18 +380,17 @@ def xr_edges2cell(ds_IcD, ve, dze, dzc, edge2cell_coeff_cc=None, fixed_vol_norm=
 
 def xr_calc_edge2edge_viacell_coeff(ds_IcD):
     # FIXME: Continue here
+    raise NotImplementedError("method not yet implemented")
     edge2edge_viacell_coeff = ()
     return edge2edge_viacell_coeff
 
+
 def xr_edges2edges_via_cell(ds_IcD, vn_e, dze='const'):
     # FIXME: Continue here
+    raise NotImplementedError("method not yet implemented")
     out_vn_e = ()
     return out_vn_e
 
-def xr_edges2edges_via_cell(ds_IcD, vn_e, scalar, dze='const'):
-    # FIXME: Continue here
-    out_vn_e = ()
-    return out_vn_e
 
 ## Divergence