Language can be fr/en, update README.md

README.md

@@ -1,21 +1,65 @@
 # xarray backend for Selafin formats
 
+Supports lazy loading by default.
+
 ## Dev guide
 
-to have the backend working in xarray, follow these steps
+To have the backend working in xarray, follow these steps:
 
 ```
 pip install xarray-selafin
 ```
 
-## Read selafin
+## Read Selafin
 
 ```python
 import xarray as xr
-ds = xr.open_dataset("input_file.slf", engine="selafin")
+ds = xr.open_dataset("tests/data/r3d_tidal_flats.slf", engine="selafin")
+ds = xr.open_dataset("tests/data/r3d_tidal_flats.slf", lang="fr", engine="selafin")  # if variables are in French
+```
+
+```
+<xarray.Dataset>
+Dimensions:  (time: 17, node: 648, plan: 21)
+Coordinates:
+    x        (node) float32 ...
+    y        (node) float32 ...
+  * time     (time) datetime64[ns] 1900-01-01 ... 1900-01-02T20:26:40
+Dimensions without coordinates: node, plan
+Data variables:
+    Z        (time, node, plan) <class 'numpy.float64'> ...
+    U        (time, node, plan) <class 'numpy.float64'> ...
+    V        (time, node, plan) <class 'numpy.float64'> ...
+    W        (time, node, plan) <class 'numpy.float64'> ...
+    MUD      (time, node, plan) <class 'numpy.float64'> ...
+Attributes:
+    title:       Sloped flume Rouse profile test
+    language:    en
+    float_size:  4
+    endian:      >
+    params:      (1, 0, 0, 0, 0, 0, 21, 5544, 0, 1)
+    ipobo:       [   1  264  263 ... 5411 5412 5413]
+    ikle2:       [[155 153 156]\n [310 307 305]\n [308 310 305]\n ...\n [537 ...
+    ikle3:       [[  155   153   156   803   801   804]\n [  310   307   305 ...
+    variables:   {'Z': ('ELEVATION Z', 'M'), 'U': ('VELOCITY U', 'M/S'), 'V':...
+    date_start:  (1900, 1, 1, 0, 0, 0)
+```
+
+## Indexing
+
+```python
+ds_last = ds.isel(time=-1)  # last frame
+```
+
+## Manipulate variables
+
+```python
+ds = ds.assign(UTIMES100=lambda x: x.U * 100)  # Add a new variable
+# ds.attrs["variables"]["UTIMES100"] = ("UTIMES100", "My/Unit")  # To provide variable name and unit (optional)
+ds.drop_vars(["W"])  # Remove variable `VELOCITY W`
 ```
 
-## Write selafin
+## Write Selafin
 
 ```python
 ds.selafin.write("output_file.slf")
@@ -40,13 +84,14 @@ ds.selafin.write("output_file.slf")
 
 All attributes are optional except `ikle2`:
 
-| Attribute  | Description                                                              | Default value            | 
-|------------|--------------------------------------------------------------------------|--------------------------|
-| title      | Serafin title                                                            | "" (empty string)        |
-| float_size | Float size                                                               | 4 (single precision)     |
-| endian     | File endianness                                                          | ">"                      |
-| params     | Table of integer parameters                                              | (can be rebuilt)         |
-| ikle2      | Connectivity table in 2D (1-indexed)                                     | -                        |
-| ikle3      | Connectivity table in 3D (1-indexed, only in 3D, optional)               | (can be rebuilt from 2D) |
-| variables  | Dictionary with variable names and units (key is variable abbreviation)  | -                        |
-| date_start | Starting date with integers                                              | (from first time serie)  |
+| Attribute  | Description                                                             | Default value            | 
+|------------|-------------------------------------------------------------------------|--------------------------|
+| title      | Serafin title                                                           | "" (empty string)        |
+| language   | Language for variable detection                                         | "en"                     |
+| float_size | Float size                                                              | 4 (single precision)     |
+| endian     | File endianness                                                         | ">"                      |
+| params     | Table of integer parameters                                             | (can be rebuilt)         |
+| ikle2      | Connectivity table in 2D (1-indexed)                                    | -                        |
+| ikle3      | Connectivity table in 3D (1-indexed, only in 3D, optional)              | (can be rebuilt from 2D) |
+| variables  | Dictionary with variable names and units (key is variable abbreviation) | -                        |
+| date_start | Starting date with integers (year to seconds)                           | (from first time serie)  |

xarray_selafin/Serafin.py

@@ -24,6 +24,10 @@
 
 logger = logging.getLogger(__name__)
 
+
+# Default language for variables
+LANG = "en"
+
 # Encoding Information Type (EIT) for Serafin title, variable names and units
 SLF_EIT = "iso-8859-1"
 
@@ -129,7 +133,7 @@ class SerafinHeader:
         [shape = nb_nodes]
     """
 
-    def __init__(self, title="", format_type="SERAFIN ", lang="en", endian=">"):
+    def __init__(self, title="", format_type="SERAFIN ", lang=LANG, endian=">"):
         """
         @param title <str>: title of the simulation
         @param format_type <str>:

xarray_selafin/xarray_backend.py

@@ -16,8 +16,8 @@ def compute_duration_between_datetime(t0, time_serie):
     return (time_serie - t0).astype("timedelta64[s]").astype(float)
 
 
-def read_serafin(f):
-    resin = Serafin.Read(f, "en")
+def read_serafin(f, lang):
+    resin = Serafin.Read(f, lang)
     resin.__enter__()
     resin.read_header()
     resin.get_time()
@@ -72,6 +72,10 @@ def write_serafin(fout, ds):
             slf_header.date = (1900, 1, 1, 0, 0, 0)
 
     # Variables
+    try:
+        slf_header.language = ds.attrs["language"]
+    except KeyError:
+        slf_header.language = Serafin.LANG
     for var in ds.data_vars:
         try:
             name, unit = ds.attrs["variables"][var]
@@ -139,7 +143,7 @@ def write_serafin(fout, ds):
     except KeyError:
         slf_header.build_params()
 
-    resout = Serafin.Write(fout, "en", overwrite=True)
+    resout = Serafin.Write(fout, slf_header.language, overwrite=True)
     resout.__enter__()
     resout.write_header(slf_header)
 
@@ -256,10 +260,12 @@ def open_dataset(
         *,
         drop_variables=None,
         decode_times=True,
+        # Below are custom arguments
         lazy_loading=True,
+        lang=Serafin.LANG,
     ):
         # Initialize SELAFIN reader
-        slf = read_serafin(filename_or_obj)
+        slf = read_serafin(filename_or_obj, lang)
         is_2d = slf.header.is_2d
 
         # Prepare dimensions, coordinates, and data variables
@@ -307,6 +313,7 @@ def open_dataset(
         ds = xr.Dataset(data_vars=data_vars, coords=coords)
 
         ds.attrs["title"] = slf.header.title.decode(Serafin.SLF_EIT).strip()
+        ds.attrs["language"] = slf.header.language
         ds.attrs["float_size"] = slf.header.float_size
         ds.attrs["endian"] = slf.header.endian
         ds.attrs["params"] = slf.header.params