Difference between revisions of "Python PDS4 Tools"

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Python 2.6+ or 3.3+
 
Python 2.6+ or 3.3+
  
pds4_read: None <br>
+
pds4_read: [http://www.numpy.org/ NumPy] <br>
 
pds4_viewer: [http://www.numpy.org/ NumPy], [http://www.matplotlib.org/ matplotlib]
 
pds4_viewer: [http://www.numpy.org/ NumPy], [http://www.matplotlib.org/ matplotlib]
 
You may use <tt>pds4_read</tt> to read-in data without any extra packages; <tt>pds4_viewer</tt> requires recent versions of the additional packages.
 
 
==== Optional Features ====
 
 
pds4_read: [http://www.numpy.org/ NumPy]<br>
 
Recommended for Arrays and Tables containing GROUP fields to allow for multi-dimensional indexing. Can result in significant improvements in memory usage and read-in speed for some data structures.<br>
 
 
pds4_viewer: None
 
  
 
=== Supported Data Structures ===
 
=== Supported Data Structures ===
Line 35: Line 26:
  
 
The table below lists the main [[Filling_Out_the_File_Area_Observational_Classes#Data_Structures|PDS4 data structures]] and the current status. <br><br>
 
The table below lists the main [[Filling_Out_the_File_Area_Observational_Classes#Data_Structures|PDS4 data structures]] and the current status. <br><br>
Read-in column indicates support by <tt>pds4_read()</tt> <br>  
+
Read-in column indicates support by <tt>pds4_tools.read()</tt> <br>  
Display columns indicate support by <tt>pds4_viewer()</tt>.  
+
Display columns indicate support by <tt>pds4_tools.view()</tt>.  
  
 
{| class="wikitable" style="text-align: center; width: 800px; "  
 
{| class="wikitable" style="text-align: center; width: 800px; "  
Line 45: Line 36:
 
! Display as Image
 
! Display as Image
 
! Display Columns as Plot
 
! Display Columns as Plot
 +
|-
 +
| style="text-align: left;" | Header
 +
| Yes
 +
| No
 +
| No
 +
| No
 
|-
 
|-
 
| style="text-align: left;" | Array  
 
| style="text-align: left;" | Array  
Line 50: Line 47:
 
| Yes
 
| Yes
 
| Yes, N-dims
 
| Yes, N-dims
| Under Development
+
| Yes, 1-D only
 
|-
 
|-
 
| style="text-align: left;" | Array_2D  
 
| style="text-align: left;" | Array_2D  
Line 56: Line 53:
 
| Yes
 
| Yes
 
| Yes
 
| Yes
| Under Development
+
| No
 
|-
 
|-
 
| style="text-align: left;" | Array_2D_*  
 
| style="text-align: left;" | Array_2D_*  
Line 62: Line 59:
 
| Yes
 
| Yes
 
| Yes
 
| Yes
| Under Development
+
| No
 
|-
 
|-
 
| style="text-align: left;" | Array_3D
 
| style="text-align: left;" | Array_3D
Line 68: Line 65:
 
| Yes
 
| Yes
 
| Yes
 
| Yes
| Under Development
+
| No
 
|-
 
|-
 
| style="text-align: left;" | Array_3D_*
 
| style="text-align: left;" | Array_3D_*
Line 74: Line 71:
 
| Yes
 
| Yes
 
| Yes
 
| Yes
| Under Development
+
| No
 
|-
 
|-
 
| style="text-align: left;" | Table_Character
 
| style="text-align: left;" | Table_Character
Line 80: Line 77:
 
| Yes
 
| Yes
 
| No
 
| No
| Under Development
+
| Yes
 
|-
 
|-
 
| style="text-align: left;" | Table_Binary
 
| style="text-align: left;" | Table_Binary
Line 86: Line 83:
 
| Yes
 
| Yes
 
| No  
 
| No  
| Under Development
+
| Yes
 
|-
 
|-
 
| style="text-align: left;" | Table_Delimited
 
| style="text-align: left;" | Table_Delimited
Line 92: Line 89:
 
| Yes
 
| Yes
 
| No
 
| No
| Under Development
+
| Yes
 +
|-
 +
| style="text-align: left;" | Composite_Structure
 +
| No
 +
| No
 +
| No
 +
| No
 
|}
 
|}
 +
 +
=== User Manual ===
 +
 +
Online [https://pdssbn.astro.umd.edu/tools/pds4_tools_docs/current/ usage documentation], both for scientists and for developers, is available.
  
 
=== Download ===
 
=== Download ===
  
Download the ZIP file [[Media:PDS4_tools-0.52.zip|File:PDS4_tools-0.52.zip]]. Released on April 4, 2016.
+
Download the ZIP file <span class="plainlinks">[https://pdssbn.astro.umd.edu/toolsrc/readpds_python/1.3/PDS4_tools-1.3.zip File:PDS4 tools-1.3.zip]</span>. Released on October 10, 2021.
 
 
Note: This is software that is still actively being developed.  
 
  
 
Note: A distributable version of the viewer only, which does not require Python, is [[PDS4 Viewer|available]].
 
Note: A distributable version of the viewer only, which does not require Python, is [[PDS4 Viewer|available]].
Line 107: Line 112:
 
==== Option 1 ====
 
==== Option 1 ====
  
Use "<tt>pip install PDS4_tools-0.52.zip</tt>" or "<tt>easy_install PDS4_tools-0.52.zip</tt>". You can also extract the ZIP file and use "<tt>python /path/to/extracted/setup.py install</tt>". Note that there is no uninstall script provided (although "<tt>pip uninstall pds4_tools</tt>" should work), and that this tool will be updated in the future.
+
Use "<tt>pip install PDS4_tools-1.3.zip</tt>"  
  
 
==== Option 2 ====
 
==== Option 2 ====
Line 115: Line 120:
 
<pre>
 
<pre>
 
import sys
 
import sys
sys.path.extend(['/path/to/your/extraction/directory'])
+
sys.path.extend([r'/path/to/extraction_directory/'])
  
# On a windows machine use backslashes (/) instead of windows' normal forward slashes to specify paths
+
import pds4_tools
 
</pre>
 
</pre>
  
 
=== Example Usage ===
 
=== Example Usage ===
 +
 +
'''See also the [https://pdssbn.astro.umd.edu/tools/pds4_tools_docs/current/ User Manual].'''
  
 
==== pds4_read ====
 
==== pds4_read ====
  
Import via "<tt>from pds4_tools import pds4_read</tt>". You may then call <tt>pds4_read</tt> from your own code.  The following is the docstring for <tt>pds4_read</tt>:
+
Import via "<tt>import pds4_tools</tt>". You may then call <tt>pds4_tools.read()</tt> from your own code.  The following is the docstring for <tt>pds4_tools.read()</tt>:
  
 
<pre>
 
<pre>
    Reads PDS4 compliant data into a `StructureList`.
+
        Reads PDS4 compliant data into a `StructureList`.
 +
 
 +
        Given a PDS4 label, reads the PDS4 data described in the label and
 +
        associated label meta data into a `StructureList`, with each PDS4 data
 +
        structure (e.g. Array_2D, Table_Binary, etc) as its own `Structure`. By
 +
        default all data structures described in the label are immediately
 +
        read into memory.
 +
 
 +
        Notes
 +
        -----
 +
        Python 2 v. Python 3: Non-data strings (label, meta data, etc)  in
 +
        Python 2 will be decoded to ``unicode`` and in Python 3 they will
 +
        be decoded to ``str``. The return type of all data strings is
 +
        controlled by *decode_strings*.
  
    Given a PDS4 label, reads the PDS4 data described in the label and
+
        Remote URLs are downloaded into an on-disk cache which is cleared on
    associated label meta data into a `StructureList`, with each PDS4 data
+
        Python interpreter exit.
    structure (e.g. Array_2D, Table_Binary, etc) as its own `Structure`. By
+
 
    default all data structures described in the label are immediately
+
        Parameters
    read into memory.
+
        ----------
 +
        filename : str or unicode
 +
            The filename, including full or relative path, or a remote
 +
            URL to the PDS4 label describing the data.
 +
        quiet : bool, int or str, optional
 +
            If True, suppresses all info/warnings from being output to stdout.
 +
            Supports log-level style options for more fine grained control.
 +
            Defaults to False.
 +
        lazy_load : bool, optional
 +
            If True, then the data of each PDS4 data structure will not be
 +
            read-in to memory until the first attempt to access it. Additionally,
 +
            for remote URLs, the data is not downloaded until first access.
 +
            Defaults to False.
 +
        no_scale : bool, optional
 +
            If True, returned data will be exactly as written in the data file,
 +
            ignoring offset or scaling values. Defaults to False.
 +
        decode_strings : bool, optional
 +
            If True, strings data types contained in the returned data will be
 +
            decoded to the a unicode in Python 2, and to the str type in
 +
            Python 3. If False, leaves string types as byte strings.
 +
            Defaults to True.
  
    Notes
+
        Returns
    -----
+
        -------
    Header and Stream Text data structures are currently unsupported
+
        StructureList
    and will be skipped on read-in.
+
            Contains PDS4 data `Structure`'s, each of which contains the data,
 +
            the meta data and the label portion describing that data structure.
 +
            `StructureList` can be treated/accessed/used like a ``dict`` or
 +
            ``list``.
  
    Python 2 v. Python 3: All data strings are returned as byte strings. In
+
        Examples
    Python 2 non-data strings (e.g. meta data, labels, etc) are byte
+
        --------
    strings and in Python 3 they are unicode strings.
 
  
    Parameters
+
         Below we document how to read data described by an example label
    ----------
+
         which has two data structures, an Array_2D_Image and a Table_Binary.
    filename : str
+
         An outline of the label, including the array and a table with 3
         The filename, including full or relative path if necessary, of
+
         fields, is given.
         the PDS4 label describing the data.
 
    quiet : bool, optional
 
        Suppresses all info/warnings from being output.
 
    lazy_load : bool, optional
 
         If True, then the data of each PDS4 data structure will not be
 
        read-in to memory until the first attempt to access it. Defaults
 
        to False.
 
    no_scale: bool, optional
 
        Returned data will be directly as written in the data file,
 
         ignoring offset or scaling values. Defaults to False.
 
    use_numpy : bool, optional
 
        Returned data will be an `np.ndarray` and use NumPy data types.
 
        Defaults to True if NumPy is installed.
 
  
    Returns
+
         >>> # Local file
    -------
+
         >>> struct_list = pds4_tools.read('/path/to/Example_Label.xml')
    StructureList
 
         Contains PDS4 data `Structure`s, each of which contains the data,
 
         the meta data and the label portion describing that data structure.
 
        `StructureList` can be treated/accessed/used like a ``dict`` or
 
        ``list``.
 
  
    Examples
+
        >>> # Remote URL
    --------
+
        >>> struct_list = pds4_tools.read('https://url.com/Example_Label.xml')
  
    Below we document how to read data described by an example label
+
        Example Label Outline::
    which has two data structures, an Array_2D_Image and a Table_Binary.
 
    An outline of the label, including the array and a table with 3
 
    fields, is given.
 
  
    >>> struct_list = pds4_read('/path/to/Example_Label.xml')
+
          Array_2D_Image: unnamed
 +
          Table_Binary: Observations
 +
              Field: order
 +
              Field: wavelength
 +
              Group: unnamed
 +
                  Field: pos_vector
  
    Example Label Outline:
+
        All below documentation assumes that the above outlined label,
 +
        containing an array that does not have a name indicated in the label,
 +
        and a table that has the name 'Observations' with 3 fields as shown,
 +
        has been read-in.
  
         Array_2D_Image: unnamed
+
         Accessing Example Structures:
        Table_Binary: Observations
 
            Field: order
 
            Field: wavelength
 
            Group: unnamed
 
                Field: pos_vector
 
  
    All below documentation assumes that the above outlined label,
+
            To access the data structures in `StructureList`, which is returned
    containing an array that does not have a name indicated in the label,
+
            by `pds4_read()`, you may use any combination of ``dict``-like or
    and a table that has the name 'Observations' with 3 fields as shown,
+
            ``list``-like access.
    has been read-in.
 
  
    Accessing Example Structures:
+
            >>> unnamed_array = struct_list[0]
 +
            >>>              or struct_list['ARRAY_0']
  
        To access the data structures in `StructureList`, which is returned
+
            >>> obs_table = struct_list[1]
        by pds4_read(), you may use any combination of `dict` or `list`.
+
            >>>          or struct_list['Observations']
  
         >>> unnamed_array = struct_list[0]
+
         Label or Structure Overview:
        >>>              or struct_list['ARRAY_0']
 
  
        >>> obs_table = struct_list[1]
+
            To see a summary of the data structures, which for Arrays shows the
        >>>          or struct_list['Observations']
+
            type and dimensions of the array, and for Tables shows the type
 +
            and number of fields, you may use the `StructureList.info()` method.
 +
            Calling `Structure.info()` on a specific ``Structure`` instead will
 +
            provide a more detailed summary, including all Fields for a table.
  
    Label or Structure Overview:
+
            >>> struct_list.info()
 +
            >>> unnamed_array.info()
 +
            >>> obs_table.info()
  
         To see a summary of the data structures, which for Arrays shows the
+
         Accessing Example Label data:
        type and dimensions of the array, and for Tables shows the type
 
        and number of fields, you may use the info() method. Calling
 
        info() on a specific `Structure` instead of `StructureList` will
 
        provide a more detailed summary, including all Fields for a table.
 
  
        >>> struct_list.info()
+
            To access the read-in data, as an array-like (subclass of ``ndarray``),
        >>> unnamed_array.info()
+
            you can use the data attribute for a PDS4 Array data structure, or
        >>> obs_table.info()
+
            list-like and the field() method to access a field for a table.
  
    Accessing Example Label data:
+
            >>> # PDS4 Arrays
 +
            >>> unnamed_array.data
  
        To access the read-in data, as an array-like (either list,
+
            >>> # PDS4 Table fields
        array.array or ndarray), you can use the data attribute for a
+
            >>> obs_table['wavelength']
        PDS4 Array data structure, or the field() method to access a field
+
            >>> obs_table.field('wavelength')
        for a table.
 
  
        >>> unnamed_array.data
+
            >>> # PDS4 Table records
        >>> obs_table.field('wavelength')
+
            >>> obs_table[0:1000]
        >>> obs_table.field('pos_vector')
 
  
    Accessing Example Label meta data:
+
        Accessing Example Label meta data:
  
        You can access all meta data in the label for a given PDS4 data
+
            You can access all meta data in the label for a given PDS4 data
        structure or field via the `OrderedDict` meta_data attribute. The
+
            structure or field via the ``OrderedDict`` meta_data attribute. The
        below examples use the 'description' element.
+
            below examples use the 'description' element.
  
        >>> unnamed_array.meta_data['description']
+
            >>> unnamed_array.meta_data['description']
  
        >>> obs_table.field('wavelength').meta_data['description']
+
            >>> obs_table.field('wavelength').meta_data['description']
        >>> obs_table.field('pos_vector').meta_data['description']
+
            >>> obs_table.field('pos_vector').meta_data['description']
  
    Accessing Example Label:
+
        Accessing Example Label:
  
        The XML for a label is also accessible via the label attribute,
+
            The XML for a label is also accessible via the label attribute,
        either the entire label or for each PDS4 data structure.
+
            either the entire label or for each PDS4 data structure.
  
        Entire label:
+
            Entire label:
            >>> struct_list.label
+
                >>> struct_list.label
  
        Part of label describing Observations table:
+
            Part of label describing Observations table:
            >>> struct_list['Observations'].label
+
                >>> struct_list['Observations'].label
            >>> struct_list[1].label
+
                >>> struct_list[1].label
  
        The returned object is similar to an ElementTree instance. It is
+
            The returned object is similar to an ElementTree instance. It is
        searchable via find() and findall() methods and XPATH. Consult
+
            searchable via `Label.find()` and `Label.findall()` methods and XPATH.
        ElementTree manual for more details. For example,
+
            Consult ``ElementTree`` manual for more details. For example,
  
        >>> struct_list.label.findall('.//disp:Display_Settings')
+
            >>> struct_list.label.findall('.//disp:Display_Settings')
  
        Will find all elements in the entire label named 'Display_Settings'
+
            Will find all elements in the entire label named 'Display_Settings'
        which are in the 'disp' namespace. You can additionally use the
+
            which are in the 'disp' prefix's namespace. You can additionally use the
        to_dict() and to_string() methods.
+
            `Label.to_dict()` and `Label.to_string()` methods.
 
</pre>
 
</pre>
  
Line 265: Line 288:
  
 
<pre>
 
<pre>
""" Basic pds4_read example """
+
""" Basic Reader example """
  
from pds4_tools import pds4_read
+
import pds4_tools
  
structures = pds4_read('/path/to/label.xml')
+
structures = pds4_tools.read('/path/to/label.xml')
  
 
structures.info()
 
structures.info()
Line 283: Line 306:
  
 
field_data = table.field('field_name') # or
 
field_data = table.field('field_name') # or
field_data = table.fields[0]
+
field_data = table.fields[0]
 +
 
 +
record_data = table[0:50]
  
 
# Array data access
 
# Array data access
Line 314: Line 339:
 
==== pds4_viewer ====
 
==== pds4_viewer ====
  
Import via "<tt>from pds4_tools import pds4_viewer</tt>". To display the data structures (such as images, spectra, or tables) in a label you may then call <tt>pds4_viewer</tt> from the Python interpreter, with or without any arguments:
+
Import via "<tt>import pds4_tools</tt>". To display the data structures (such as images, spectra, or tables) in a label you may then call <tt>pds4_tools.view()</tt> from the Python interpreter, with or without any arguments:
  
 
<pre>
 
<pre>
Line 325: Line 350:
 
     desired label to be read-in and displayed.
 
     desired label to be read-in and displayed.
  
     Parameters:
+
     Parameters
 
+
    ----------
        filename : str, optional
+
    filename : str or unicode, optional
            The filename, including full or relative path if necessary, of
+
        The filename, including full or relative path if necessary, of
            the PDS4 label describing the data to be viewed.
+
        the PDS4 label describing the data to be viewed.
        from_existing_structures : StructureList, optional
+
    from_existing_structures : StructureList, optional
            An existing StructureList, as returned by pds4_read(), to view. Takes
+
        An existing StructureList, as returned by pds4_read(), to view. Takes
            precedence if given together with filename.
+
        precedence if given together with filename.
        lazy_load : bool, optional
+
    lazy_load : bool, optional
            Do not read-in data of each data structure until attempt to view said
+
        Do not read-in data of each data structure until attempt to view said
            data structure. Defaults to True.
+
        data structure. Defaults to True.
        quiet : bool, optional
+
    quiet : bool, int or str, optional
            If True, suppresses all info/warnings from being output and displayed.
+
        Suppresses all info/warnings from being output and displayed. Supports
            Defaults to False.
+
        log-level style options for more fine grained control. Defaults to False.
 
</pre>
 
</pre>
  
It is not necessary to include the filename parameter for <tt>pds4_viewer</tt>, you may simplify call it without any options or arguments and a GUI will open from which you can open labels.  
+
It is not necessary to include the filename parameter for <tt>pds4_tools.view</tt>, you may simplify call it without any options or arguments and a GUI will open from which you can open labels.  
  
You may also call <tt>pds4_viewer</tt> from another module or script. All the above arguments are available as optional named parameters. A basic example usage is as follows:
+
You may also call <tt>pds4_tools.view</tt> from another module or script. All the above arguments are available as optional named parameters. A basic example usage is as follows:
  
 
<pre>
 
<pre>
""" Basic pds4_viewer example """
+
""" Basic Viewer example """
  
from pds4_tools import pds4_read, pds4_viewer
+
import pds4_tools
  
pds4_viewer()
+
pds4_tools.view()
  
 
# or
 
# or
  
pds4_viewer('/path/to/label.xml')
+
pds4_tools.view('/path/to/label.xml')
  
 
# or  
 
# or  
  
struct_list = pds4_read('label.xml')
+
struct_list = pds4_tools.view('label.xml')
pds4_viewer(from_existing_structures=struct_list) # Won't re-read the data
+
pds4_tools.view(from_existing_structures=struct_list) # Won't re-read the data
 
</pre>
 
</pre>
 +
 +
 +
 +
[[Category:Python]]
 +
[[Category:Tools]]

Latest revision as of 06:28, 7 November 2021

Python and PDS4

This document describes the current status and usage of Python tools developed at PDS-SBN to read and visualize PDS4 data in Python. Please note that a PDS4 reader and visualizer for IDL is also available.

Reading and Displaying PDS4 Data

Introduction

This section describes a Python package that can read and display PDS4 data and meta data. In the future this tool is expected to support all PDS4 data structures, currently support is limited to structures given in the Supported Data Structures section. The package expects valid PDS4 labels formatted according to the PDS4 Standard.

Contact Lev Nagdimunov with questions or comments regarding this code or its description.

Requirements

Python 2.6+ or 3.3+

pds4_read: NumPy
pds4_viewer: NumPy, matplotlib

Supported Data Structures

PDS4 Data Standards >= v1.0 are supported.
PDS3 Data Standards are not supported.

The table below lists the main PDS4 data structures and the current status.

Read-in column indicates support by pds4_tools.read()
Display columns indicate support by pds4_tools.view().

Structure Read-in Display as Table Display as Image Display Columns as Plot
Header Yes No No No
Array Yes Yes Yes, N-dims Yes, 1-D only
Array_2D Yes Yes Yes No
Array_2D_* Yes Yes Yes No
Array_3D Yes Yes Yes No
Array_3D_* Yes Yes Yes No
Table_Character Yes Yes No Yes
Table_Binary Yes, except BitFields Yes No Yes
Table_Delimited Yes Yes No Yes
Composite_Structure No No No No

User Manual

Online usage documentation, both for scientists and for developers, is available.

Download

Download the ZIP file File:PDS4 tools-1.3.zip. Released on October 10, 2021.

Note: A distributable version of the viewer only, which does not require Python, is available.

Installation

Option 1

Use "pip install PDS4_tools-1.3.zip"

Option 2

Extract the downloaded file to a directory Python can find. To use it follow the instructions in Example Usage except with the following lines first,

import sys
sys.path.extend([r'/path/to/extraction_directory/'])

import pds4_tools

Example Usage

See also the User Manual.

pds4_read

Import via "import pds4_tools". You may then call pds4_tools.read() from your own code. The following is the docstring for pds4_tools.read():

        Reads PDS4 compliant data into a `StructureList`.

        Given a PDS4 label, reads the PDS4 data described in the label and
        associated label meta data into a `StructureList`, with each PDS4 data
        structure (e.g. Array_2D, Table_Binary, etc) as its own `Structure`. By
        default all data structures described in the label are immediately
        read into memory.

        Notes
        -----
        Python 2 v. Python 3: Non-data strings (label, meta data, etc)  in
        Python 2 will be decoded to ``unicode`` and in Python 3 they will
        be decoded to ``str``. The return type of all data strings is
        controlled by *decode_strings*.

        Remote URLs are downloaded into an on-disk cache which is cleared on
        Python interpreter exit.

        Parameters
        ----------
        filename : str or unicode
            The filename, including full or relative path, or a remote
            URL to the PDS4 label describing the data.
        quiet : bool, int or str, optional
            If True, suppresses all info/warnings from being output to stdout.
            Supports log-level style options for more fine grained control.
            Defaults to False.
        lazy_load : bool, optional
            If True, then the data of each PDS4 data structure will not be
            read-in to memory until the first attempt to access it. Additionally,
            for remote URLs, the data is not downloaded until first access.
            Defaults to False.
        no_scale : bool, optional
            If True, returned data will be exactly as written in the data file,
            ignoring offset or scaling values. Defaults to False.
        decode_strings : bool, optional
            If True, strings data types contained in the returned data will be
            decoded to the a unicode in Python 2, and to the str type in
            Python 3. If False, leaves string types as byte strings.
            Defaults to True.

        Returns
        -------
        StructureList
            Contains PDS4 data `Structure`'s, each of which contains the data,
            the meta data and the label portion describing that data structure.
            `StructureList` can be treated/accessed/used like a ``dict`` or
            ``list``.

        Examples
        --------

        Below we document how to read data described by an example label
        which has two data structures, an Array_2D_Image and a Table_Binary.
        An outline of the label, including the array and a table with 3
        fields, is given.

        >>> # Local file
        >>> struct_list = pds4_tools.read('/path/to/Example_Label.xml')

        >>> # Remote URL
        >>> struct_list = pds4_tools.read('https://url.com/Example_Label.xml')

        Example Label Outline::

           Array_2D_Image: unnamed
           Table_Binary: Observations
               Field: order
               Field: wavelength
               Group: unnamed
                   Field: pos_vector

        All below documentation assumes that the above outlined label,
        containing an array that does not have a name indicated in the label,
        and a table that has the name 'Observations' with 3 fields as shown,
        has been read-in.

        Accessing Example Structures:

            To access the data structures in `StructureList`, which is returned
            by `pds4_read()`, you may use any combination of ``dict``-like or
            ``list``-like access.

            >>> unnamed_array = struct_list[0]
            >>>              or struct_list['ARRAY_0']

            >>> obs_table = struct_list[1]
            >>>          or struct_list['Observations']

        Label or Structure Overview:

            To see a summary of the data structures, which for Arrays shows the
            type and dimensions of the array, and for Tables shows the type
            and number of fields, you may use the `StructureList.info()` method.
            Calling `Structure.info()` on a specific ``Structure`` instead will
            provide a more detailed summary, including all Fields for a table.

            >>> struct_list.info()
            >>> unnamed_array.info()
            >>> obs_table.info()

        Accessing Example Label data:

            To access the read-in data, as an array-like (subclass of ``ndarray``),
            you can use the data attribute for a PDS4 Array data structure, or
            list-like and the field() method to access a field for a table.

            >>> # PDS4 Arrays
            >>> unnamed_array.data

            >>> # PDS4 Table fields
            >>> obs_table['wavelength']
            >>> obs_table.field('wavelength')

            >>> # PDS4 Table records
            >>> obs_table[0:1000]

        Accessing Example Label meta data:

            You can access all meta data in the label for a given PDS4 data
            structure or field via the ``OrderedDict`` meta_data attribute. The
            below examples use the 'description' element.

            >>> unnamed_array.meta_data['description']

            >>> obs_table.field('wavelength').meta_data['description']
            >>> obs_table.field('pos_vector').meta_data['description']

        Accessing Example Label:

            The XML for a label is also accessible via the label attribute,
            either the entire label or for each PDS4 data structure.

            Entire label:
                >>> struct_list.label

            Part of label describing Observations table:
                >>> struct_list['Observations'].label
                >>> struct_list[1].label

            The returned object is similar to an ElementTree instance. It is
            searchable via `Label.find()` and `Label.findall()` methods and XPATH.
            Consult ``ElementTree`` manual for more details. For example,

            >>> struct_list.label.findall('.//disp:Display_Settings')

            Will find all elements in the entire label named 'Display_Settings'
            which are in the 'disp' prefix's namespace. You can additionally use the
            `Label.to_dict()` and `Label.to_string()` methods.

Usage is described above. A basic usage example is as follows:

""" Basic Reader example """

import pds4_tools

structures = pds4_tools.read('/path/to/label.xml')

structures.info()

0 - Array_3D_Spectrum 'table_name' (3 axes, 21 x 10 x 36)
1 - Table_Binary 'array_name' (5 fields x 1000 records)

# Table data access
table = structures['table_name'] # or
table = structures[0]

table.info()

field_data = table.field('field_name') # or
field_data = table.fields[0] 

record_data = table[0:50]

# Array data access
array = structures['array_name'] # or
array = structures[1]

array_data = array.data

# Meta-data access
field_meta = table.field('field_name').meta_data # or
field_meta = table.fields[0].meta_data
array_meta = array.meta_data

print field_meta['description']
print field_meta['unit']
print array_meta['local_identifier']

# Label access
label = structures.label # Full label
label = table.label      # Label section describing the table object

display_settings = label.findall('.//disp:Display_Settings')

display_dict = display_settings.to_dict()
label_dict = label.to_dict()
label_string = label.to_string()

pds4_viewer

Import via "import pds4_tools". To display the data structures (such as images, spectra, or tables) in a label you may then call pds4_tools.view() from the Python interpreter, with or without any arguments:

    Displays PDS4 compliant data in a GUI.

    Given a PDS4 label, displays PDS4 data described in the label and
    associated label meta data in a GUI. By default all data structures described
    in the label are read-in and displayed. Can be called without any
    parameters, opening a GUI that has a File->Open function to select
    desired label to be read-in and displayed.

    Parameters
    ----------
    filename : str or unicode, optional
        The filename, including full or relative path if necessary, of
        the PDS4 label describing the data to be viewed.
    from_existing_structures : StructureList, optional
        An existing StructureList, as returned by pds4_read(), to view. Takes
        precedence if given together with filename.
    lazy_load : bool, optional
        Do not read-in data of each data structure until attempt to view said
        data structure. Defaults to True.
    quiet : bool, int or str, optional
        Suppresses all info/warnings from being output and displayed. Supports
        log-level style options for more fine grained control. Defaults to False.

It is not necessary to include the filename parameter for pds4_tools.view, you may simplify call it without any options or arguments and a GUI will open from which you can open labels.

You may also call pds4_tools.view from another module or script. All the above arguments are available as optional named parameters. A basic example usage is as follows:

""" Basic Viewer example """

import pds4_tools

pds4_tools.view()

# or

pds4_tools.view('/path/to/label.xml')

# or 

struct_list = pds4_tools.view('label.xml')
pds4_tools.view(from_existing_structures=struct_list) # Won't re-read the data