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oceanmodeling / xarray-selafin

An xarray engine for opening Selafin files (TELEMAC)
https://pypi.org/project/xarray-selafin/
The Unlicense
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telemac xarray xarray-extension

readme

Available on pypi CI

xarray backend for Selafin formats

Supports lazy loading by default.

Dev guide

To have the backend working in xarray, follow these steps:

pip install xarray-selafin

or, if you are using, conda:

conda install -c conda-forge xarray_selafin

Read Selafin

import xarray as xr
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

ds_last = ds.isel(time=-1)  # last frame

Manipulate variables

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

ds.selafin.write("output_file.slf")

DataSet content

Dimensions

Coordinates

Coordinate Description
x East mesh coordinates
y North mesh coordinates
time Datetime serie

Attributes

All attributes are optional except ikle2:

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)