# `gdal mdim convert`

Added in version 3.11.

Convert a multidimensional dataset.

## Synopsis

    Usage: gdal mdim convert [OPTIONS] <INPUT> <OUTPUT>

    Convert a multidimensional dataset.

    Positional arguments:
      -i, --input <INPUT>                                  Input raster or multidimensional raster dataset [required]
      -o, --output <OUTPUT>                                Output multidimensional raster dataset (created by algorithm) [required]

    Common Options:
      -h, --help                                           Display help message and exit
      --json-usage                                         Display usage as JSON document and exit
      --config <KEY>=<VALUE>                               Configuration option [may be repeated]
      -q, --quiet                                          Quiet mode (no progress bar)

    Options:
      -f, --of, --format, --output-format <OUTPUT-FORMAT>  Output format
      --co, --creation-option <KEY>=<VALUE>                Creation option [may be repeated]
      --overwrite                                          Whether overwriting existing output is allowed
      --array <ARRAY-SPEC>                                 Select a single array instead of converting the whole dataset. [may be repeated]
      --array-option <KEY>=<VALUE>                         Option passed to GDALGroup::GetMDArrayNames() to filter arrays. [may be repeated]
      --group <GROUP-SPEC>                                 Select a single group instead of converting the whole dataset. [may be repeated]
      --subset <SUBSET-SPEC>                               Select a subset of the data. [may be repeated]
      --scale-axes <SCALEAXES-SPEC>                        Applies a integral scale factor to one or several dimensions [may be repeated]
      --strict                                             Turn warnings into failures.

    Advanced Options:
      --oo, --open-option <KEY>=<VALUE>                    Open options [may be repeated]
      --if, --input-format <INPUT-FORMAT>                  Input formats [may be repeated]

## Description

gdal mdim convert can be used to convert multidimensional data between different formats.

The following options are available:

### Standard options

-f, --of, --format, --output-format <OUTPUT-FORMAT>

  Select the output format. This can be a format that supports multidimensional output (such as NetCDF: Network Common Data Form, Multidimensional VRT), 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.

--co, --creation-option <KEY>=<VALUE>

  Many formats have one or more optional creation options that can be used to control particulars about the file created.

  The creation options available vary by format driver, and some simple formats have no creation options at all. A list of options supported for a format can be listed with the --format command line option but the documentation for the format is the definitive source of information on driver creation options. See Raster drivers format specific documentation for legal creation options for each format.

  Array-level creation options may be passed by prefixing them with `ARRAY:`. See `GDALGroup::CopyFrom()` for further details regarding such options.

--overwrite

  Allow program to overwrite existing target file or dataset. Otherwise, by default, gdal errors out if the target file or dataset already exists.

--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}][,resample=yes][,transpose=[{axis1},{axis2},...][,view={view_expr}]

  The following options are processed in that order:

  - `resample=yes` asks for the array to run through `GDALMDArray::GetResampled()`.

  - [{axis1},{axis2},...] is the argument of `GDALMDArray::Transpose()`.

      For example, transpose=[1,0] switches the axis order of a 2D array. See Example 6.

  - {view_expr} is the value of the viewExpr argument of `GDALMDArray::GetView()`. See Example 5.

  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.

--array-option <NAME>=<VALUE>

  Option passed to `GDALGroup::GetMDArrayNames()` to filter reported arrays. Such option is format specific. Consult driver documentation. This option may be used several times.

--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 content 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]`

--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 monotonically sorted. <subset_spec> follows exactly the OGC WCS 2.0 KVP encoding 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)

  Beware that dimension name is case sensitive.

  Several subsetting operations along different dimensions can be specified by repeating the option.

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

  See Example 2 or Example 3.

--scale-axes <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, but limited to integer scale factors.

  That is `<dim1_name>(<scale_factor>)`.

  Several scaling operations along different dimensions can be specified by repeating the option.

  Using --scale-axes is incompatible with specifying a view option in --array.

  See Example 4.

--strict

  By default, some failures during the translation are tolerated, such as not being able to write group attributes. When setting this option, such failures will cause the process to fail.

### Advanced options

--oo, --open-option <NAME>=<VALUE>

  Dataset open option (format specific).

  May be repeated.

--if, --input-format <format>

  Format/driver name to be attempted to open the input file(s). It is generally not necessary to specify it, but it can be used to skip automatic driver detection, when it fails to select the appropriate driver. This option can be repeated several times to specify several candidate drivers. Note that it does not force those drivers to open the dataset. In particular, some drivers have requirements on file extensions.

  May be repeated.

## Examples

### Example 1: Convert a netCDF file to a multidimensional VRT file

    gdal mdim convert in.nc out.vrt

### Example 2: Extract a 2D slice of a time,Y,X array

    gdal mdim convert in.nc out.tif --subset "time(\"2010-01-01\")" --array temperature

### Example 3: Extract a a 3D chunk from a time-indexed GRIB file into a multiband GeoTIFF.

    gdal mdim convert /vsicurl/https://tgftp.nws.noaa.gov/SL.us008001/ST.opnl/DF.gr2/DC.ndfd/AR.conus/VP.001-003/ds.qpf.bin tst.tif --subset "TIME(1763164800,1763251200)" --array QPF_0-SFC --co COMPRESS=DEFLATE

### Example 4: Subsample along x and y axis

    gdal mdim convert in.nc out.nc --scale-axes "x(2),y(2)"

### Example 5: Reorder the values of an array

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

    gdal mdim convert in.nc out.nc --array "name=temperature,view=[:,::-1,:]"

### Example 6: Transpose an array that has X,Y,time dimension order to time,Y,X

    gdal mdim convert in.nc out.nc --array "name=temperature,transpose=[2,1,0]"