.. DO NOT EDIT.
.. THIS FILE WAS AUTOMATICALLY GENERATED BY SPHINX-GALLERY.
.. TO MAKE CHANGES, EDIT THE SOURCE PYTHON FILE:
.. "gallery/example_concat.py"
.. LINE NUMBERS ARE GIVEN BELOW.

.. only:: html

    .. note::
        :class: sphx-glr-download-link-note

        :ref:`Go to the end <sphx_glr_download_gallery_example_concat.py>`
        to download the full example code.

.. rst-class:: sphx-glr-example-title

.. _sphx_glr_gallery_example_concat.py:


Concatenating drifter datasets
==============================

.. GENERATED FROM PYTHON SOURCE LINES 5-13

.. code-block:: Python

    import numpy as np
    import lzma
    import matplotlib.pyplot as plt
    import cartopy.crs as ccrs
    import xarray as xr
    import pandas as pd
    import trajan as ta








.. GENERATED FROM PYTHON SOURCE LINES 14-15

Importing a dataset with two drifters in the Barents Sea

.. GENERATED FROM PYTHON SOURCE LINES 15-21

.. code-block:: Python

    with lzma.open('barents.nc.xz') as barents:
        ds = xr.open_dataset(barents)
        ds.load()

    assert 'obs' in ds.dims





.. rst-class:: sphx-glr-script-out

 .. code-block:: none

    2025-06-24 13:41:18 fv-az1280-93 h5py._conv[2414] DEBUG Creating converter from 7 to 5
    2025-06-24 13:41:18 fv-az1280-93 h5py._conv[2414] DEBUG Creating converter from 5 to 7
    2025-06-24 13:41:18 fv-az1280-93 h5py._conv[2414] DEBUG Creating converter from 7 to 5
    2025-06-24 13:41:18 fv-az1280-93 h5py._conv[2414] DEBUG Creating converter from 5 to 7
    2025-06-24 13:41:18 fv-az1280-93 h5py._conv[2414] DEBUG Creating converter from 3 to 5




.. GENERATED FROM PYTHON SOURCE LINES 22-23

Split into two observational datasets for this example

.. GENERATED FROM PYTHON SOURCE LINES 23-32

.. code-block:: Python


    ds = ds.rename(drifter_names='trajectory').traj.condense_obs()
    print(ds)

    d1 = ds.isel(trajectory=0).traj.to_1d().traj.to_2d()
    d2 = ds.isel(trajectory=1).traj.to_1d().traj.to_2d()
    print("d1=", d1)
    print("d2=", d2)





.. rst-class:: sphx-glr-script-out

 .. code-block:: none

    2025-06-24 13:41:18 fv-az1280-93 trajan.accessor[2414] DEBUG Detecting trajectory dimension
    2025-06-24 13:41:18 fv-az1280-93 trajan.accessor[2414] DEBUG Detecting time-variable for "obs"..
    2025-06-24 13:41:18 fv-az1280-93 trajan.accessor[2414] DEBUG Detected obs-dim: obs, detected time-variable: time.
    2025-06-24 13:41:18 fv-az1280-93 trajan.accessor[2414] DEBUG Detected un-structured (2D) trajectory dataset
    2025-06-24 13:41:18 fv-az1280-93 trajan.traj2d[2414] DEBUG Condensing 2287 observations.
    2025-06-24 13:41:18 fv-az1280-93 trajan.traj2d[2414] DEBUG Condensed observations from: 2287 to 2287
    <xarray.Dataset> Size: 128kB
    Dimensions:     (trajectory: 2, obs: 2287)
    Coordinates:
        trajectory  (trajectory) <U16 128B 'UIB-2022-TILL-01' 'UIB-2022-TILL-02'
      * obs         (obs) int64 18kB 0 1 2 3 4 5 6 ... 2281 2282 2283 2284 2285 2286
    Data variables:
        lon         (trajectory, obs) float64 37kB 29.85 29.83 29.82 ... 21.14 21.15
        lat         (trajectory, obs) float64 37kB 77.3 77.31 77.31 ... 74.58 74.58
        time        (trajectory, obs) datetime64[ns] 37kB 2022-10-07T00:00:38 ......
    Attributes: (12/13)
        Conventions:          CF-1.10
        featureType:          trajectory
        geospatial_lat_min:   74.5454462
        geospatial_lat_max:   77.4774768
        geospatial_lon_min:   17.2058074
        geospatial_lon_max:   29.8523485
        ...                   ...
        time_coverage_end:    2022-11-23T13:30:28
        creator_email:        gauteh@met.no, knutfd@met.no
        creator_name:         Gaute Hope and Knut Frode Dagestad
        creator_url:          https://github.com/OpenDrift/opendrift
        summary:              Two drifters in the Barents Sea. One stranded at Ho...
        title:                Barents Sea drifters
    2025-06-24 13:41:18 fv-az1280-93 trajan.accessor[2414] DEBUG Detecting trajectory dimension
    2025-06-24 13:41:18 fv-az1280-93 trajan.accessor[2414] DEBUG Single trajectory, a trajectory dimension will be added
    2025-06-24 13:41:18 fv-az1280-93 trajan.accessor[2414] DEBUG Using trajectory_id variable name (trajectory) as trajectory dimension name
    2025-06-24 13:41:18 fv-az1280-93 trajan.accessor[2414] DEBUG Detecting time-variable for "obs"..
    2025-06-24 13:41:18 fv-az1280-93 trajan.accessor[2414] DEBUG Detected obs-dim: obs, detected time-variable: time.
    2025-06-24 13:41:18 fv-az1280-93 trajan.accessor[2414] DEBUG Detected un-structured (2D) trajectory dataset
    2025-06-24 13:41:18 fv-az1280-93 trajan.accessor[2414] DEBUG Detecting trajectory dimension
    2025-06-24 13:41:18 fv-az1280-93 trajan.accessor[2414] DEBUG Detected obs-dim: time, detected time-variable: time.
    2025-06-24 13:41:18 fv-az1280-93 trajan.accessor[2414] DEBUG Detected structured (1D) trajectory dataset
    2025-06-24 13:41:18 fv-az1280-93 trajan.accessor[2414] DEBUG Detecting trajectory dimension
    2025-06-24 13:41:18 fv-az1280-93 trajan.accessor[2414] DEBUG Single trajectory, a trajectory dimension will be added
    2025-06-24 13:41:18 fv-az1280-93 trajan.accessor[2414] DEBUG Using trajectory_id variable name (trajectory) as trajectory dimension name
    2025-06-24 13:41:18 fv-az1280-93 trajan.accessor[2414] DEBUG Detecting time-variable for "obs"..
    2025-06-24 13:41:18 fv-az1280-93 trajan.accessor[2414] DEBUG Detected obs-dim: obs, detected time-variable: time.
    2025-06-24 13:41:18 fv-az1280-93 trajan.accessor[2414] DEBUG Detected un-structured (2D) trajectory dataset
    2025-06-24 13:41:18 fv-az1280-93 trajan.accessor[2414] DEBUG Detecting trajectory dimension
    2025-06-24 13:41:18 fv-az1280-93 trajan.accessor[2414] DEBUG Detected obs-dim: time, detected time-variable: time.
    2025-06-24 13:41:18 fv-az1280-93 trajan.accessor[2414] DEBUG Detected structured (1D) trajectory dataset
    d1= <xarray.Dataset> Size: 33kB
    Dimensions:     (trajectory: 1, obs: 1027)
    Coordinates:
      * trajectory  (trajectory) <U16 64B 'UIB-2022-TILL-01'
      * obs         (obs) int64 8kB 0 1 2 3 4 5 6 ... 1021 1022 1023 1024 1025 1026
    Data variables:
        lon         (trajectory, obs) float64 8kB 29.85 29.83 29.82 ... 25.11 25.11
        lat         (trajectory, obs) float64 8kB 77.3 77.31 77.31 ... 76.57 76.57
        time        (trajectory, obs) datetime64[ns] 8kB 2022-10-07T00:00:38 ... ...
    Attributes: (12/13)
        Conventions:          CF-1.10
        featureType:          trajectory
        geospatial_lat_min:   74.5454462
        geospatial_lat_max:   77.4774768
        geospatial_lon_min:   17.2058074
        geospatial_lon_max:   29.8523485
        ...                   ...
        time_coverage_end:    2022-11-23T13:30:28
        creator_email:        gauteh@met.no, knutfd@met.no
        creator_name:         Gaute Hope and Knut Frode Dagestad
        creator_url:          https://github.com/OpenDrift/opendrift
        summary:              Two drifters in the Barents Sea. One stranded at Ho...
        title:                Barents Sea drifters
    d2= <xarray.Dataset> Size: 73kB
    Dimensions:     (trajectory: 1, obs: 2287)
    Coordinates:
      * trajectory  (trajectory) <U16 64B 'UIB-2022-TILL-02'
      * obs         (obs) int64 18kB 0 1 2 3 4 5 6 ... 2281 2282 2283 2284 2285 2286
    Data variables:
        lon         (trajectory, obs) float64 18kB 27.82 27.8 27.78 ... 21.14 21.15
        lat         (trajectory, obs) float64 18kB 77.11 77.11 77.11 ... 74.58 74.58
        time        (trajectory, obs) datetime64[ns] 18kB 2022-10-07T00:00:40 ......
    Attributes: (12/13)
        Conventions:          CF-1.10
        featureType:          trajectory
        geospatial_lat_min:   74.5454462
        geospatial_lat_max:   77.4774768
        geospatial_lon_min:   17.2058074
        geospatial_lon_max:   29.8523485
        ...                   ...
        time_coverage_end:    2022-11-23T13:30:28
        creator_email:        gauteh@met.no, knutfd@met.no
        creator_name:         Gaute Hope and Knut Frode Dagestad
        creator_url:          https://github.com/OpenDrift/opendrift
        summary:              Two drifters in the Barents Sea. One stranded at Ho...
        title:                Barents Sea drifters




.. GENERATED FROM PYTHON SOURCE LINES 33-34

Concatenate two 2D datasets (with observation dimension).

.. GENERATED FROM PYTHON SOURCE LINES 34-42

.. code-block:: Python


    dc = xr.concat((d1, d2), dim='trajectory')
    dc = dc.traj.condense_obs()
    print(dc)

    assert np.all(ds.lat.values[~np.isnan(ds.lat.values)] ==
                  dc.lat.values[~np.isnan(dc.lat.values)])





.. rst-class:: sphx-glr-script-out

 .. code-block:: none

    2025-06-24 13:41:18 fv-az1280-93 trajan.accessor[2414] DEBUG Detecting trajectory dimension
    2025-06-24 13:41:18 fv-az1280-93 trajan.accessor[2414] DEBUG Detecting time-variable for "obs"..
    2025-06-24 13:41:18 fv-az1280-93 trajan.accessor[2414] DEBUG Detected obs-dim: obs, detected time-variable: time.
    2025-06-24 13:41:18 fv-az1280-93 trajan.accessor[2414] DEBUG Detected un-structured (2D) trajectory dataset
    2025-06-24 13:41:18 fv-az1280-93 trajan.traj2d[2414] DEBUG Condensing 2287 observations.
    2025-06-24 13:41:18 fv-az1280-93 trajan.traj2d[2414] DEBUG Condensed observations from: 2287 to 2287
    <xarray.Dataset> Size: 128kB
    Dimensions:     (trajectory: 2, obs: 2287)
    Coordinates:
      * trajectory  (trajectory) <U16 128B 'UIB-2022-TILL-01' 'UIB-2022-TILL-02'
      * obs         (obs) int64 18kB 0 1 2 3 4 5 6 ... 2281 2282 2283 2284 2285 2286
    Data variables:
        lon         (trajectory, obs) float64 37kB 29.85 29.83 29.82 ... 21.14 21.15
        lat         (trajectory, obs) float64 37kB 77.3 77.31 77.31 ... 74.58 74.58
        time        (trajectory, obs) datetime64[ns] 37kB 2022-10-07T00:00:38 ......
    Attributes: (12/13)
        Conventions:          CF-1.10
        featureType:          trajectory
        geospatial_lat_min:   74.5454462
        geospatial_lat_max:   77.4774768
        geospatial_lon_min:   17.2058074
        geospatial_lon_max:   29.8523485
        ...                   ...
        time_coverage_end:    2022-11-23T13:30:28
        creator_email:        gauteh@met.no, knutfd@met.no
        creator_name:         Gaute Hope and Knut Frode Dagestad
        creator_url:          https://github.com/OpenDrift/opendrift
        summary:              Two drifters in the Barents Sea. One stranded at Ho...
        title:                Barents Sea drifters




.. GENERATED FROM PYTHON SOURCE LINES 43-44

Concatenating two 1D datasets, with observations at different times.

.. GENERATED FROM PYTHON SOURCE LINES 44-52

.. code-block:: Python


    d1 = d1.traj.to_1d(
    )  # trivial conversion since `d1` only contains a single trajectory. No need for gridtime.
    d2 = d2.traj.to_1d()  # Also trivial for d2.
    print(d1)

    assert 'obs' not in d1.dims





.. rst-class:: sphx-glr-script-out

 .. code-block:: none

    2025-06-24 13:41:18 fv-az1280-93 trajan.accessor[2414] DEBUG Detecting trajectory dimension
    2025-06-24 13:41:18 fv-az1280-93 trajan.accessor[2414] DEBUG Detecting time-variable for "obs"..
    2025-06-24 13:41:18 fv-az1280-93 trajan.accessor[2414] DEBUG Detected obs-dim: obs, detected time-variable: time.
    2025-06-24 13:41:18 fv-az1280-93 trajan.accessor[2414] DEBUG Detected un-structured (2D) trajectory dataset
    2025-06-24 13:41:18 fv-az1280-93 trajan.accessor[2414] DEBUG Detecting trajectory dimension
    2025-06-24 13:41:18 fv-az1280-93 trajan.accessor[2414] DEBUG Detecting time-variable for "obs"..
    2025-06-24 13:41:18 fv-az1280-93 trajan.accessor[2414] DEBUG Detected obs-dim: obs, detected time-variable: time.
    2025-06-24 13:41:18 fv-az1280-93 trajan.accessor[2414] DEBUG Detected un-structured (2D) trajectory dataset
    <xarray.Dataset> Size: 25kB
    Dimensions:     (trajectory: 1, time: 1027)
    Coordinates:
      * time        (time) datetime64[ns] 8kB 2022-10-07T00:00:38 ... 2022-11-17T...
      * trajectory  (trajectory) <U16 64B 'UIB-2022-TILL-01'
    Data variables:
        lon         (trajectory, time) float64 8kB 29.85 29.83 29.82 ... 25.11 25.11
        lat         (trajectory, time) float64 8kB 77.3 77.31 77.31 ... 76.57 76.57
    Attributes: (12/13)
        Conventions:          CF-1.10
        featureType:          trajectory
        geospatial_lat_min:   74.5454462
        geospatial_lat_max:   77.4774768
        geospatial_lon_min:   17.2058074
        geospatial_lon_max:   29.8523485
        ...                   ...
        time_coverage_end:    2022-11-23T13:30:28
        creator_email:        gauteh@met.no, knutfd@met.no
        creator_name:         Gaute Hope and Knut Frode Dagestad
        creator_url:          https://github.com/OpenDrift/opendrift
        summary:              Two drifters in the Barents Sea. One stranded at Ho...
        title:                Barents Sea drifters




.. GENERATED FROM PYTHON SOURCE LINES 53-54

Concatenating two 1D datasets will cause a lot of NaNs to be inserted.

.. GENERATED FROM PYTHON SOURCE LINES 54-60

.. code-block:: Python

    dc = xr.concat((d1, d2), dim='trajectory')
    print(dc)

    assert np.all(ds.lat.values[~np.isnan(ds.lat.values)] ==
                  dc.lat.values[~np.isnan(dc.lat.values)])





.. rst-class:: sphx-glr-script-out

 .. code-block:: none

    <xarray.Dataset> Size: 127kB
    Dimensions:     (trajectory: 2, time: 3163)
    Coordinates:
      * time        (time) datetime64[ns] 25kB 2022-10-07T00:00:38 ... 2022-11-23...
      * trajectory  (trajectory) <U16 128B 'UIB-2022-TILL-01' 'UIB-2022-TILL-02'
    Data variables:
        lon         (trajectory, time) float64 51kB 29.85 nan 29.83 ... 21.14 21.15
        lat         (trajectory, time) float64 51kB 77.3 nan 77.31 ... 74.58 74.58
    Attributes: (12/13)
        Conventions:          CF-1.10
        featureType:          trajectory
        geospatial_lat_min:   74.5454462
        geospatial_lat_max:   77.4774768
        geospatial_lon_min:   17.2058074
        geospatial_lon_max:   29.8523485
        ...                   ...
        time_coverage_end:    2022-11-23T13:30:28
        creator_email:        gauteh@met.no, knutfd@met.no
        creator_name:         Gaute Hope and Knut Frode Dagestad
        creator_url:          https://github.com/OpenDrift/opendrift
        summary:              Two drifters in the Barents Sea. One stranded at Ho...
        title:                Barents Sea drifters




.. GENERATED FROM PYTHON SOURCE LINES 61-62

Converting to 2D and condensing the dataset will give a cleaner result.

.. GENERATED FROM PYTHON SOURCE LINES 62-67

.. code-block:: Python


    dc = xr.concat((d1.traj.to_2d(), d2.traj.to_2d()),
                   dim='trajectory').traj.condense_obs()
    print(dc)
    assert dc.sizes['obs'] == ds.sizes['obs']




.. rst-class:: sphx-glr-script-out

 .. code-block:: none

    2025-06-24 13:41:18 fv-az1280-93 trajan.accessor[2414] DEBUG Detecting trajectory dimension
    2025-06-24 13:41:18 fv-az1280-93 trajan.accessor[2414] DEBUG Detected obs-dim: time, detected time-variable: time.
    2025-06-24 13:41:18 fv-az1280-93 trajan.accessor[2414] DEBUG Detected structured (1D) trajectory dataset
    2025-06-24 13:41:18 fv-az1280-93 trajan.accessor[2414] DEBUG Detecting trajectory dimension
    2025-06-24 13:41:18 fv-az1280-93 trajan.accessor[2414] DEBUG Detected obs-dim: time, detected time-variable: time.
    2025-06-24 13:41:18 fv-az1280-93 trajan.accessor[2414] DEBUG Detected structured (1D) trajectory dataset
    2025-06-24 13:41:18 fv-az1280-93 trajan.accessor[2414] DEBUG Detecting trajectory dimension
    2025-06-24 13:41:18 fv-az1280-93 trajan.accessor[2414] DEBUG Detecting time-variable for "obs"..
    2025-06-24 13:41:18 fv-az1280-93 trajan.accessor[2414] DEBUG Detected obs-dim: obs, detected time-variable: time.
    2025-06-24 13:41:18 fv-az1280-93 trajan.accessor[2414] DEBUG Detected un-structured (2D) trajectory dataset
    2025-06-24 13:41:18 fv-az1280-93 trajan.traj2d[2414] DEBUG Condensing 2287 observations.
    2025-06-24 13:41:18 fv-az1280-93 trajan.traj2d[2414] DEBUG Condensed observations from: 2287 to 2287
    <xarray.Dataset> Size: 128kB
    Dimensions:     (trajectory: 2, obs: 2287)
    Coordinates:
      * trajectory  (trajectory) <U16 128B 'UIB-2022-TILL-01' 'UIB-2022-TILL-02'
      * obs         (obs) int64 18kB 0 1 2 3 4 5 6 ... 2281 2282 2283 2284 2285 2286
    Data variables:
        lon         (trajectory, obs) float64 37kB 29.85 29.83 29.82 ... 21.14 21.15
        lat         (trajectory, obs) float64 37kB 77.3 77.31 77.31 ... 74.58 74.58
        time        (trajectory, obs) datetime64[ns] 37kB 2022-10-07T00:00:38 ......
    Attributes: (12/13)
        Conventions:          CF-1.10
        featureType:          trajectory
        geospatial_lat_min:   74.5454462
        geospatial_lat_max:   77.4774768
        geospatial_lon_min:   17.2058074
        geospatial_lon_max:   29.8523485
        ...                   ...
        time_coverage_end:    2022-11-23T13:30:28
        creator_email:        gauteh@met.no, knutfd@met.no
        creator_name:         Gaute Hope and Knut Frode Dagestad
        creator_url:          https://github.com/OpenDrift/opendrift
        summary:              Two drifters in the Barents Sea. One stranded at Ho...
        title:                Barents Sea drifters





.. rst-class:: sphx-glr-timing

   **Total running time of the script:** (0 minutes 0.153 seconds)


.. _sphx_glr_download_gallery_example_concat.py:

.. only:: html

  .. container:: sphx-glr-footer sphx-glr-footer-example

    .. container:: sphx-glr-download sphx-glr-download-jupyter

      :download:`Download Jupyter notebook: example_concat.ipynb <example_concat.ipynb>`

    .. container:: sphx-glr-download sphx-glr-download-python

      :download:`Download Python source code: example_concat.py <example_concat.py>`

    .. container:: sphx-glr-download sphx-glr-download-zip

      :download:`Download zipped: example_concat.zip <example_concat.zip>`


.. only:: html

 .. rst-class:: sphx-glr-signature

    `Gallery generated by Sphinx-Gallery <https://sphinx-gallery.github.io>`_