.. _strip:

strip
=====

Strip plots show the distribution of values in a numerical column optionally grouped by categorical columns, where dots are used to show the underlying data points.

Usage
-----

.. code-block:: text 

    gurita strip [-h] [-x COLUMN] [-y COLUMN] [--hue COLUMN] ... other arguments ...

Arguments
---------

.. list-table::
   :widths: 25 20 10
   :header-rows: 1
   :class: tight-table

   * - Argument
     - Description
     - Reference
   * - ``-h``
     - display help
     - :ref:`help <strip_help>`
   * - * ``-x COLUMN``
       * ``--xaxis COLUMN``
     - select column for the X axis
     - :ref:`X axis <strip_column_selection>`
   * - * ``-y COLUMN``
       * ``--yaxis COLUMN``
     - select column for the Y axis
     - :ref:`Y axis <strip_column_selection>`
   * - ``--orient {v,h}``
     - Orientation of plot. Allowed values: v = vertical, h = horizontal. Default: v.
     - :ref:`orient <strip_orient>`
   * - ``--order VALUE [VALUE ...]``
     - controlling the order of the plotted strips 
     - :ref:`order <strip_order>`
   * - ``--hue COLUMN``
     - colour and/or group columns by hue 
     - :ref:`hue <strip_hue>`
   * - ``--dodge``
     - separate hue levels along the categorical axis  
     - :ref:`dodge <strip_dodge>`
   * - ``--hueorder COLUMN [COLUMN ...]``
     - order of hue columns
     - :ref:`hue order <strip_hueorder>`
   * - ``--logx``
     - log scale X axis (only relevant with ``--orient h``) 
     - :ref:`log X axis <strip_log>`
   * - ``--logy``
     - log scale Y axis 
     - :ref:`log Y axis <strip_log>`
   * - ``--xlim BOUND BOUND``
     - range limit X axis 
     - :ref:`limit X axis <strip_range>`
   * - ``--ylim BOUND BOUND``
     - range limit Y axis 
     - :ref:`limit Y axis <strip_range>`
   * - ``--frow COLUMN``
     - column to use for facet rows 
     - :ref:`facet rows <strip_facets>`
   * - ``--fcol COLUMN``
     - column to use for facet columns 
     - :ref:`facet columns <strip_facets>`
   * - ``--fcolwrap INT``
     - wrap the facet column at this width, to span multiple rows
     - :ref:`facet wrap <strip_facets>`

See also
--------

Similar functionality to strip plots are provided by:

 * :doc:`Box plots <box/>`
 * :doc:`Violin plots <violin/>`
 * :doc:`Swarm plots <swarm/>` 
 * :doc:`Boxen plots <boxen/>` 

Strip plots are based on Seaborn's `catplot <https://seaborn.pydata.org/generated/seaborn.catplot.html>`_ library function, using the ``kind="strip"`` option.

Simple example
--------------

Strip plot of the ``age`` numerical column from the ``titanic.csv`` input file:

.. code-block:: bash

    gurita strip -y age < titanic.csv 

The output of the above command is written to ``strip.age.png``:

.. image:: ../docs/_images/strip.age.png 
       :width: 600px
       :height: 600px
       :align: center
       :alt: Strip plot showing the distribution of age for the titanic data set

|

The plotted numerical column can be divided into groups based on a categorical column.
In the following example the distribution of ``age`` is shown for each value in the ``class`` column:

.. code-block:: bash

    gurita strip -y age -x class < titanic.csv 

The output of the above command is written to ``strip.class.age.png``:

.. image:: ../docs/_images/strip.class.age.png 
       :width: 600px
       :height: 600px
       :align: center
       :alt: Strip plot showing the distribution of age for each class in the titanic data set

|

.. _strip_help:

Getting help
------------

The full set of command line arguments for strip plots can be obtained with the ``-h`` or ``--help``
arguments:

.. code-block:: bash

    gurita strip -h

.. _strip_column_selection:

Selecting columns to plot
--------------------------

.. code-block:: 

  -x COLUMN, --xaxis COLUMN
  -y COLUMN, --yaxis COLUMN

Strip plots can be plotted for numerical columns and optionally grouped by categorical columns.

If no categorical column is specified, a single column strip plot will be generated showing
the distribution of the numerical column.

.. note:: 

    .. _strip_orient:

    By default the orientation of the strip plot is vertical. In this scenario
    the numerical column is specified by ``-y``, and the (optional) categorical column is specified
    by ``-x``.
    
    However, the orientation of the strip plot can be made horizontal using the ``--orient h`` argument.
    In this case the sense of the X and Y axes are swapped from the default, and thus
    the numerical column is specified by ``-x``, and the (optional) categorical column is specified
    by ``-y``.

In the following example the distribution of ``age`` is shown for each value in the ``class`` column,
where the boxes are plotted horizontally:

.. code-block:: bash

    gurita strip -x age -y class --orient h < titanic.csv

.. image:: ../docs/_images/strip.age.class.png 
       :width: 600px
       :height: 600px
       :align: center
       :alt: Strip plot showing the distribution of age for each class in the titanic data set, shown horizontally

|

.. _strip_order:

Controlling the order of the strips
-----------------------------------

.. code-block:: 

    --order VALUE [VALUE ...]

By default the order of the categorical columns displayed in the strip plot is determined from their occurrence in the input data.
This can be overridden with the ``--order`` argument, which allows you to specify the exact ordering of columns based on their values. 

In the following example the strip columns of the ``class`` column are displayed in the order of ``First``, ``Second``, ``Third``:

.. code-block:: bash

    gurita strip -y age -x class --order First Second Third < titanic.csv

.. image:: ../docs/_images/strip.class.age.order.png 
       :width: 600px
       :height: 600px
       :align: center
       :alt: Strip plot showing the distribution of age for each class in the titanic data set, shown in a specified order

|

.. _strip_hue:

Colour and/or group columns with hue
------------------------------------

.. code-block:: 

  --hue COLUMN

Each box can be coloured and optionally subdivided into additional categories with the ``--hue`` argument.
     
The following example generates a strip plot showing the distribution of the age of titanic passengers across the three different ticket classes, where each class is coloured differently:
       
.. code-block:: bash 
     
    gurita strip -y age -x class --hue class < titanic.csv
     
.. image:: ../docs/_images/strip.class.age.hue.png
       :width: 700px
       :height: 600px 
       :align: center
       :alt: Strip plot showing the distribution of age for each class in the titanic data set, grouped by class and coloured by class 

|

In the following example the distribution of ``age`` is shown for each value in the ``class`` column, and further sub-divided by the ``sex`` column:

.. code-block:: bash

    gurita strip -y age -x class --hue sex < titanic.csv

.. image:: ../docs/_images/strip.class.age.sex.png 
       :width: 600px
       :height: 600px
       :align: center
       :alt: Strip plot showing the distribution of age for each class in the titanic data set, grouped by class and sex 

|

.. _strip_dodge:

As the previous example demonstrates, when ``--hue`` is used, by default all hue levels are shown mixed together in the same strip.
However, you might want to show each hue level in its own strip. This can be achieved with the ``--dodge`` command.

The ``--dodge`` argument will separate hue levels along the categorical axis, rather than mix them together:

.. code-block:: bash

    gurita strip -y age -x class --hue sex --dodge < titanic.csv

.. image:: ../docs/_images/strip.class.age.sex.dodge.png 
       :width: 600px
       :height: 600px
       :align: center
       :alt: Strip plot showing the distribution of age for each class in the titanic data set, grouped by class and sex, with the sex data separated into strips

|

.. _strip_hueorder:

By default the order of the columns within each hue group is determined from their occurrence in the input data. 
This can be overridden with the ``--hueorder`` argument, which allows you to specify the exact ordering of columns within each hue group, based on their values. 

In the following example the ``sex`` values are displayed in the order of ``female``, ``male``: 

.. code-block:: bash

    gurita strip -y age -x class --hue sex --hueorder female male < titanic.csv

.. image:: ../docs/_images/strip.class.age.sex.hueorder.png 
       :width: 600px
       :height: 600px
       :align: center
       :alt: Strip plot showing the distribution of age for each class in the titanic data set, grouped by class and sex, with the order of sex values specified 

|

It is also possible to use both ``--order`` and ``--hueorder`` in the same command. For example, the following command controls
the order of both the ``class`` and ``sex`` categorical columns:

.. code-block:: bash

    gurita strip -y age -x class --order First Second Third --hue sex --hueorder female male < titanic.csv

.. image:: ../docs/_images/strip.class.age.sex.order.hueorder.png 
       :width: 600px
       :height: 600px
       :align: center
       :alt: Strip plot showing the distribution of age for each class in the titanic data set, grouped by class and sex, with the order of class and sex values specified 

|

.. _strip_log:

Log scale 
---------

.. code-block:: 

  --logx
  --logy

The distribution of numerical values can be displayed in log (base 10) scale with ``--logx`` and ``--logy``. 

It only makes sense to log-scale the numerical axis (and not the categorical axis). Therefore, ``--logx`` should be used when numerical columns are selected with ``-x``, and
conversely, ``--logy`` should be used when numerical columns are selected with ``-y``.

For example, you can display a log scale strip plot for the ``age`` column grouped by ``class`` (when the distribution of ``age`` is displayed on the Y axis) like so. Note carefully that the numerical data is displayed on the Y-axis (``-y``), therefore the ``--logy`` argument should be used to log-scale the numerical distribution:

.. code-block:: bash

    gurita strip -y age -x class --logy < titanic.csv 

.. image:: ../docs/_images/strip.class.age.logy.png 
       :width: 600px
       :height: 600px
       :align: center
       :alt: Strip plot showing the distribution of age for each class in the titanic data set, grouped by class, with the Y axis in log scale 

|

.. _strip_range:

Axis range limits
-----------------

.. code-block:: 

  --xlim LOW HIGH 
  --ylim LOW HIGH

The range of displayed numerical distributions can be restricted with ``--xlim`` and ``--ylim``. Each of these flags takes two numerical values as arguments that represent the lower and upper bounds of the range to be displayed.

It only makes sense to range-limit the numerical axis (and not the categorical axis). Therefore, ``--xlim`` should be used when numerical columns are selected with ``-x``, and
conversely, ``--ylim`` should be used when numerical columns are selected with ``-y``.

For example, you can display range-limited range for the ``age`` column grouped by ``class`` (when the distribution of ``age`` is displayed on the Y axis) like so.
Note carefully that the numerical 
data is displayed on the Y-axis (``-y``), therefore the ``--ylim`` argument should be used to range-limit the distribution: 

.. code-block:: bash

    gurita strip -y age -x class --ylim 10 30 < titanic.csv

.. image:: ../docs/_images/strip.class.age.ylim.png 
       :width: 600px
       :height: 600px
       :align: center
       :alt: Strip plot showing the distribution of age for each class in the titanic data set, grouped by class, with the Y axis limited to the range 10 to 30 inclusive

.. _strip_facets:

Facets
------

.. code-block:: 

 --frow COLUMN
 --fcol COLUMN
 --fcolwrap INT

Strip plots can be further divided into facets, generating a matrix of strip plots, where a numerical value is
further categorised by up to 2 more categorical columns.

See the :doc:`facet documentation <facets/>` for more information on this feature.

.. code-block:: bash

    gurita strip -y age -x class --fcol sex < titanic.csv

.. image:: ../docs/_images/strip.class.age.sex.facet.png
       :width: 600px
       :height: 300px 
       :align: center
       :alt: Strip plot showing the distribution of age for each class in the titanic data set, grouped by class, with facet columns determined by sex 

|