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Mapping Files Without Barcodes and/or Primers
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In some circumstances, users may need to generate a mapping file that does not contain barcodes and/or primers. To generate such a mapping file, the header and column for "BarcodeSequence" is removed and "LinkerPrimerSequence" fields can be left empty. An example of such a file is below (note that the tabs are still present for the empty "LinkerPrimerSequence" field):
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In some circumstances, users may need to generate a mapping file that does not contain barcodes and/or primers. To generate such a mapping file, fields for "BarcodeSequence" and "LinkerPrimerSequence" can be left empty. An example of such a file is below (note that the tabs are still present for the empty "BarcodeSequence" and "LinkerPrimerSequence" fields):
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* #SampleID LinkerPrimerSequence Treatment DOB Description
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* #SampleID BarcodeSequence LinkerPrimerSequence Treatment DOB Description
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* #Example mapping file for the QIIME analysis package. These 9 samples are from a study of the effects of
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* #exercise and diet on mouse cardiac physiology (Crawford, et al, PNAS, 2009).
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* PC.354 Control 20061218 Control_mouse__I.D._354
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OTU tables are sample x observation matrices, and are central to a lot of downstream analysis in QIIME. These are generated by ``pick_otus_through_otu_table.py`` but can also be generated externally from QIIME (e.g., exported from MG-RAST for metagenomic analysis with QIIME). These are used in scripts such as ``beta_diversity_through_plots.py``, ``alpha_rarefaction.py``, and ``summarize_taxa_through_plots.py.py``.
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OTU tables are sample x observation matrices, and are central to a lot of downstream analysis in QIIME. These are generated by ``pick_de_novo_otus.py`` but can also be generated externally from QIIME (e.g., exported from MG-RAST for metagenomic analysis with QIIME). These are used in scripts such as ``beta_diversity_through_plots.py``, ``alpha_rarefaction.py``, and ``summarize_taxa_through_plots.py.py``.
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OTU Table overview
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The QIIME parameters files is used to pass per-script parameters to the QIIME 'workflow' scripts. An example is provided as ``Qiime/qiime_parameters.txt``.
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This file is used to give workflow script users control over the parameters to the individual scripts without having an extremely complex and hard to maintain interface to the workflow scripts. Users should copy the example ``qiime_parameters.txt`` script to the directory where they are performing their analysis, and edit the values in this file accordingly. This copy will be referred to as the user's working ``qiime_parameters.txt`` file. The parameters are defined as ``script_name:parameter_name``, followed by a tab, and then the value. For example::
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align_seqs:alignment_method pynast
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This indicates that the ``--alignment_method`` will be set to ``pynast`` when calling ``align_seqs.py``. To get information on what a parameter in the ``qiime_parameters.txt`` file is, you should call the script name followed by ``-h`` to access the usage information for that script. In the above example, you could call::
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python align_seqs.py -h
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Boolean options are specified by passing ``True`` or ``False`` after the tab. For example::
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parallel:retain_temp_files False
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When a parameter is not followed by an option, that indicates that it will not be passed to the script resulting in the default value being used instead. For example::
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This results in no ``--blast_db`` parameter being passed to ``align_seqs.py``. Alternatively, you can delete this line from your working ``qiime_parameters.txt`` file.
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You can find information on the QIIME workflow scripts at:
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* `pick_otus_through_otu_table.py <../scripts/pick_otus_through_otu_table.html>`_
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* `alpha_rarefaction.py <../scripts/alpha_rarefaction.html>`_
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* `beta_diversity_through_plots.py <../scripts/beta_diversity_through_plots.html>`_
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* `jackknifed_beta_diversity.py <../scripts/jackknifed_beta_diversity.html>`_
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The QIIME parameters files is used to pass per-script parameters to the QIIME 'workflow' scripts. You can find details on these files in :doc:`qiime_parameters_files`.
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Some scripts which compare paired samples, including `transform_coordinate_matrices.py <../scripts/transform_coordinate_matrices.html>`_ and `compare_taxa_summaries.py <../scripts/compare_taxa_summaries.html>`_, take a parameter, ``--sample_id_map_fp``, which is necessary when comparing data sets with different sample IDs. This file, a *sample id map* (**which is different than a QIIME mapping file**), describes how to map from the sample IDs associated with the input data to a new sample id that will be consistent across the data sets being compared. For example, if your first data set contains samples ``S1``, ``S2``, and ``S3``, and these should be paired with samples ``T1``, ``T2``, and ``T3`` in your second data set, your *sample id map* might look like::
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The reason for this format is that it's usually sample metadata from one or more columns in the QIIME mapping files associated with each data set that allows you to match samples to one another. With this format you can select one or more columns from each QIIME mapping file (concatenating some fields, if necessary) to build the sample id map.
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To clarify, this format maps from *input* sample id to *new* sample id, **not** from *sample id in matrix 1* to *sample id in matrix 2*.