.. _examples:

#############
Examples
#############

Sigma0_detrend example
======================

Open a SAFE file sentinel 1 and calculate the sigma0_detrend

.. code-block:: python

    import xsar
    import xsarsea
    safe_file = 'S1A_IW_GRDH_1SDV_20170907T103020_20170907T103045_018268_01EB76_992F.SAFE'
    ds = xsar.open_dataset(safe_file)
    sar_ds = ds[0]
    sar_ds['sigma0_detrend'] = xsarsea.sigma0_detrend(sar_ds.sigma0, sar_ds.incidence)

Result:

.. code-block:: text

 <xarray.Dataset>
 Dimensions:         (atrack: 16800, pol: 2, xtrack: 25200)
 Coordinates:
  * pol             (pol) object 'VV' 'VH'
  * atrack          (atrack) int64 0 1 2 3 4 5 ... 16795 16796 16797 16798 16799
  * xtrack          (xtrack) int64 0 1 2 3 4 5 ... 25195 25196 25197 25198 25199
 Data variables:
    digital_number  (pol, atrack, xtrack) float32 dask.array<chunksize=(1, 5600, 25200), meta=np.ndarray>
    time            (atrack) datetime64[ns] 2017-09-07T10:30:20.936409 ... 20...
    longitude       (atrack, xtrack) float32 dask.array<chunksize=(5600, 25200), meta=np.ndarray>
    latitude        (atrack, xtrack) float32 dask.array<chunksize=(5600, 25200), meta=np.ndarray>
    incidence       (atrack, xtrack) float32 dask.array<chunksize=(5600, 25200), meta=np.ndarray>
    elevation       (atrack, xtrack) float32 dask.array<chunksize=(5600, 25200), meta=np.ndarray>
    sigma0_raw      (pol, atrack, xtrack) float32 dask.array<chunksize=(1, 5600, 25200), meta=np.ndarray>
    nesz            (pol, atrack, xtrack) float32 dask.array<chunksize=(1, 5600, 25200), meta=np.ndarray>
    gamma0_raw      (pol, atrack, xtrack) float32 dask.array<chunksize=(1, 5600, 25200), meta=np.ndarray>
    negz            (pol, atrack, xtrack) float32 dask.array<chunksize=(1, 5600, 25200), meta=np.ndarray>
    sigma0          (pol, atrack, xtrack) float32 dask.array<chunksize=(1, 5600, 25200), meta=np.ndarray>
    gamma0          (pol, atrack, xtrack) float32 dask.array<chunksize=(1, 5600, 25200), meta=np.ndarray>
    sigma0_detrend  (pol, atrack, xtrack) float32 dask.array<chunksize=(1, 5600, 25200), meta=np.ndarray>
 Attributes:
    footprint:       POLYGON ((-67.84221143971432 20.72564283093837, -70.2216...
    coverage:        251km * 170km (xtrack * atrack )
    pixel_xtrack_m:  10.0
    pixel_atrack_m:  10.2
    ipf_version:     2.84
    swath_type:      IW
    polarizations:   VV VH
    product_type:    GRD
    mission:         SENTINEL-1
    satellite:       A
    start_date:      2017-09-07 10:30:20.936409
    stop_date:       2017-09-07 10:30:45.935264
    path:            /home/datawork-cersat-public/project/mpc-sentinel1/data/...
    denoised:        {'VH': False, 'VV': False}
    subdataset:      IW
    geometry:        {'VH': {'atrack':   atracks xtracks                     ...
    Conventions:     CF-1.7


Streaks example
======================

Use the sigma0_detrend

.. code-block:: python

    from xsarsea.streaks import streaks_direction
    streaks_direction(sar_ds.sigma0_detrend)

Result:

.. code-block:: text

    <xarray.DataArray 'angles_hist' (pol: 2, atrack: 105, xtrack: 158)>
    dask.array<concatenate, shape=(2, 105, 158), dtype=float64, chunksize=(1, 35, 158), chunktype=numpy.ndarray>
    Coordinates:
      * atrack   (atrack) float64 21.5 181.5 341.5 ... 1.634e+04 1.65e+04 1.666e+04
      * xtrack   (xtrack) float64 21.5 181.5 341.5 ... 2.482e+04 2.498e+04 2.514e+04
      * pol      (pol) object 'VV' 'VH'