.. _gdalmdimtranslate:

================================================================================
gdalmdimtranslate
================================================================================

.. versionadded:: 3.1

.. only:: html

    Converts multidimensional data between different formats, and perform subsetting.

.. Index:: gdalmdimtranslate

Synopsis
--------

.. code-block::

    gdalmdimtranslate [--help-general] [-co "NAME=VALUE"]*
                      [-of format] [-array <array_spec>]*
                      [-group <group_spec>]* 
                      [-subset <subset_spec>]* 
                      [-scaleaxes <scaleaxes_spec>]* 
                      <src_filename> <dst_filename>


Description
-----------

:program:`gdalmdimtranslate` program converts multidimensional raster between
different formats, and/or can perform selective conversion of specific arrays
and groups, and/or subsetting operations.

The following command line parameters can appear in any order.

.. program:: gdalmdimtranslate

.. option:: -of <format>

    Select the output format. This can be a format that supports multidimensional
    output (such as :ref:`raster.netcdf`, :ref:`vrt_multidimensional`), or a "classic" 2D formats, if only one single 2D array
    results of the other specified conversion operations. When this option is
    not specified, the format is guessed when possible from the extension of the
    destination filename.

.. include:: options/co.rst

.. option:: -array <array_spec>

    Instead of converting the whole dataset, select one array, and possibly
    perform operations on it. This option can be specified several times to
    operate on different arrays.

    <array_spec> may be just an array name, potentially using a fully qualified
    syntax (/group/subgroup/array_name). Or it can be a combination of options
    with the syntax:
    name={src_array_name}[,dstname={dst_array_name}][,transpose=[{axis1},{axis2},...][,view={view_expr}]

    [{axis1},{axis2},...] is the argumet of  :cpp:func:`GDALMDArray::Transpose`.
    For example, transpose=[1,0] switches the axis order of a 2D array.

    {view_expr} is the value of the *viewExpr* argument of :cpp:func:`GDALMDArray::GetView`

    When specifying a view_expr that performs a slicing or subsetting on a dimension, the
    equivalent operation will be applied to the corresponding indexing variable.

.. option:: -group <group_spec>

    Instead of converting the whole dataset, select one group, and possibly
    perform operations on it. This option can be specified several times to
    operate on different groups. If only one group is specified, its contet will be
    copied directly to the target root group. If several ones are specified,
    they are copied under the target root group

    <group_spec> may be just a group name, potentially using a fully qualified
    syntax (/group/subgroup/subsubgroup_name). Or it can be a combination of options
    with the syntax:
    name={src_group_name}[,dstname={dst_group_name}][,recursive=no]

.. option:: -subset <subset_spec>

    Performs a subsetting (trimming or slicing) operation along a dimension,
    provided that it is indexed by a 1D variable of numeric or string data type,
    and whose values are monotically sorted.
    <subset_spec> follows exactly the `OGC WCS 2.0 KVP encoding <https://portal.opengeospatial.org/files/09-147r3>`__
    for subsetting.

    That is dim_name(min_val,max_val) or dim_name(sliced_val)
    The first syntax will subset the dimension dim_name to values in the
    [min_val,max_val] range. The second syntax will slice the dimension dim_name
    to value sliced_val (and this dimension will be removed from the arrays
    that reference to it)

    Using -subset is incompatible of specifying a *view* option in -array.

.. option:: -scaleaxes <scaleaxes_spec>

    Applies a integral scale factor to one or several dimensions, that is
    extract 1 value every N values (without resampling).

    <scaleaxes_spec> follows exactly the syntax of the KVP encoding of the
    SCALEAXES parameter of
    `OGC WCS 2.0 Scaling Extension <https://portal.opengeospatial.org/files/12-039>`__,
    but limited to integer scale factors.

    That is dim1_name(scale_factor)[,dim2_name(scale_factor)]*

    Using -scaleaxes is incompatible of specifying a *view* option in -array.

.. option:: <src_dataset>

    The source dataset name.

.. option:: <dst_dataset>

    The destination file name.

C API
-----

This utility is also callable from C with :cpp:func:`GDALMultiDimTranslate`.

Examples
--------

- Convert a netCDF file to a multidimensional VRT file

.. code-block::

    $ gdalmdimtranslate in.nc out.vrt

- Extract a 2D slice of a time,Y,X array

.. code-block::

    $ gdalmdimtranslate in.nc out.tif -subset 'time("2010-01-01")' -array temperature

- Subsample along X and Y axis

.. code-block::

    $ gdalmdimtranslate in.nc out.nc -scaleaxes "X(2),Y(2)"

- Reorder the values of a time,Y,X array along the Y axis from top-to-bottom
  to bottom-to-top (or the reverse)

.. code-block::

    $ gdalmdimtranslate in.nc out.nc -array "name=temperature,view=[:,::-1,:]"

- Transpose an array that has X,Y,time dimension order to time,Y,X

.. code-block::

    $ gdalmdimtranslate in.nc out.nc -array "name=temperature,transpose=[2,1,0]"
