# biom-format.org

## Converting between file formats

The `convert` command in the biom-format project can be used to convert between biom and tab-delimited table formats. This is useful for several reasons:
  - converting biom format tables to tab-delimited tables for easy viewing in programs such as Excel
  - converting between sparse and dense biom formats (note: dense is only supported in biom-format 1.0.0)

  Note

  The tab-delimited tables are commonly referred to as the classic format tables, while BIOM formatted tables are referred to as biom tables.

## General usage examples

Convert a tab-delimited table to a HDF5 or JSON biom format. Note that you must specify the type of table here:

    biom convert -i table.txt -o table.from_txt_json.biom --table-type="OTU table" --to-json
    biom convert -i table.txt -o table.from_txt_hdf5.biom --table-type="OTU table" --to-hdf5

Convert biom format to tab-delimited table format:

    biom convert -i table.biom -o table.from_biom.txt --to-tsv

Convert biom format to classic format, including the `taxonomy` observation metadata as the last column of the classic format table. Because the BIOM format can support an arbitrary number of observation (or sample) metadata entries, and the classic format can support only a single observation metadata entry, you must specify which of the observation metadata entries you want to include in the output table:

    biom convert -i table.biom -o table.from_biom_w_taxonomy.txt --to-tsv --header-key taxonomy

Convert biom format to classic format, including the `taxonomy` observation metadata as the last column of the classic format table, but renaming that column as `ConsensusLineage`. This is useful when using legacy tools that require a specific name for the observation metadata column.:

    biom convert -i table.biom -o table.from_biom_w_consensuslineage.txt --to-tsv --header-key taxonomy --output-metadata-id "ConsensusLineage"

## Special case usage examples

### Round-tripping between biom and tsv

In specific cases, see this comment, it is still useful to convert our biom table to tsv so we can open in Excel, make some changes to the file and then convert back to biom. For this cases you should follow this steps:

- Convert from biom to txt:

      biom convert -i otu_table.biom -o otu_table.txt --to-tsv --header-key taxonomy

- Make your changes in Excel.

- Convert back to biom:

      biom convert -i otu_table.txt -o new_otu_table.biom --to-hdf5 --table-type="OTU table" --process-obs-metadata taxonomy

### Converting QIIME 1.4.0 and earlier OTU tables to BIOM format

If you are converting a QIIME 1.4.0 or earlier OTU table to BIOM format, there are a few steps to go through. First, for convenience, you might want to rename the `ConsensusLineage` column `taxonomy`. You can do this with the following command:

    sed 's/Consensus Lineage/ConsensusLineage/' < otu_table.txt | sed 's/ConsensusLineage/taxonomy/' > otu_table.taxonomy.txt

Then, you’ll want to perform the conversion including a step to convert the taxonomy string from the classic OTU table to a taxonomy list, as it’s represented in QIIME 1.4.0-dev and later:

    biom convert -i otu_table.taxonomy.txt -o otu_table.from_txt.biom --table-type="OTU table" --process-obs-metadata taxonomy --to-hdf5