Describe downloadable datasets#

This command reports various information about datasets that can be downloaded with the download command. The information is reported either as human-readable text (the default) or as a JSON object. The format can be selected with the --report-format option.

When the JSON output format is selected, the output document has the following schema:

    "<dataset name>": {
        "default_output_format": "<Datumaro format name>",
        "description": "<human-readable description>",
        "download_size": <total size of the downloaded files in bytes>,
        "home_url": "<URL of a web page describing the dataset>",
        "human_name": "<human-readable dataset name>",
        "num_classes": <number of classes in the dataset>,
        "subsets": {
            "<subset name>": {
                "num_items": <number of items in the subset>
        "version": "<version number>"

home_url may be null if there is no suitable web page for the dataset.

num_classes may be null if the dataset does not involve classification.

version currently contains the version number supplied by TFDS. In future versions of Datumaro, datasets might come from other sources; the way version numbers will be set for those is to be determined.

New object members may be added in future versions of Datumaro.


datum download describe [-h] [--report-format {text,json}]
                        [--report-file REPORT_FILE]


  • -h, --help - Print the help message and exit.

  • --report-format (text or json) - Format in which to report the information. By default, text is used.

  • --report-file (string) - File to which to write the report. By default, the report is written to the standard output stream.

Download datasets#

This command downloads a publicly available dataset and saves it to a local directory. In terms of syntax, this command is similar to convert, but instead of taking a local directory as the source, it takes a dataset ID. A list of supported datasets and output formats can be found in the --help output of this command.

Currently, the only source of datasets is the TensorFlow Datasets library. Therefore, to use this command you must install TensorFlow & TFDS, which you can do as follows:

pip install datumaro[tf,tfds]

To use a proxy for downloading, configure it with the conventional curl environment variables.


datum download get [-h] -i DATASET_ID [-f OUTPUT_FORMAT] [-o DST_DIR]
                   [--overwrite] [-s SUBSET] [-- EXTRA_EXPORT_ARGS]


  • -h, --help - Print the help message and exit.

  • -i, --dataset-id (string) - ID of the dataset to download.

  • -f, --output-format (string) - Output format. By default, the format of the original dataset is used.

  • -o, --output-dir (string) - Output directory. By default, a subdirectory in the current directory is used.

  • --overwrite - Allows overwriting existing files in the output directory, when it is not empty.

  • --subset (string) - Which subset of the dataset to save. By default, all subsets are saved. Note that due to limitations of TFDS, all subsets are downloaded even if this option is specified.

  • -- <extra export args> - Additional arguments for the format writer (use -- -h for help). Must be specified after the main command arguments.


  • Download the MNIST dataset, saving it in the ImageNet text format

    datum download get -i tfds:mnist -f imagenet_txt -- --save-images