lim added files to sphere branch

git-svn-id: http://svn.stsci.edu/svn/ssb/stsci_python/stsci_python/branches/sphere@15878 fe389314-cf27-0410-b35b-8c050e845b92

Former-commit-id: b51412b5b545598ae101152eeaed470b08616176

6 files changed, 459 insertions, 0 deletions

diff --git a/doc/source/api.rst b/doc/source/api.rst
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+API Documentation
+=================
+
+Vectors
+-------
+
+.. automodule:: vector
+   :members:
+
+Great circle arcs
+-----------------
+
+.. automodule:: great_circle_arc
+   :members:
+
+Spherical polygons
+------------------
+
+.. currentmodule:: polygon
+
+.. automodule:: polygon
+   :members:
+
+Graph operations on polygons
+----------------------------
+
+.. currentmodule:: graph
+
+.. automodule:: graph
+   :members:
diff --git a/doc/source/conf.py b/doc/source/conf.py
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+# -*- coding: utf-8 -*-
+#
+# Spherical Geometry Toolkit documentation build configuration file, created by
+# sphinx-quickstart on Tue Oct 11 09:04:48 2011.
+#
+# This file is execfile()d with the current directory set to its containing dir.
+#
+# Note that not all possible configuration values are present in this
+# autogenerated file.
+#
+# All configuration values have a default; values that are commented out
+# serve to show the default.
+
+from stsci.sphinxext.conf import *
+
+import sys, os
+
+# If extensions (or modules to document with autodoc) are in another directory,
+# add these directories to sys.path here. If the directory is relative to the
+# documentation root, use os.path.abspath to make it absolute, like shown here.
+#sys.path.insert(0, os.path.abspath('.'))
+
+# -- General configuration -----------------------------------------------------
+
+# If your documentation needs a minimal Sphinx version, state it here.
+#needs_sphinx = '1.0'
+
+# Add any Sphinx extension module names here, as strings. They can be extensions
+# coming with Sphinx (named 'sphinx.ext.*') or your custom ones.
+#extensions += ['sphinx.ext.autodoc', 'sphinx.ext.intersphinx', 'sphinx.ext.mathjax', 'sphinx.ext.viewcode']
+extensions += ['sphinx.ext.autodoc', 'sphinx.ext.intersphinx', 'sphinx.ext.pngmath', 'sphinx.ext.viewcode']
+
+# Add any paths that contain templates here, relative to this directory.
+templates_path = ['_templates']
+
+# The suffix of source filenames.
+source_suffix = '.rst'
+
+# The encoding of source files.
+#source_encoding = 'utf-8-sig'
+
+# The master toctree document.
+master_doc = 'index'
+
+# General information about the project.
+project = u'Spherical Geometry Toolkit'
+copyright = u'2011, Michael Droettboom, STScI'
+
+# The version info for the project you're documenting, acts as replacement for
+# |version| and |release|, also used in various other places throughout the
+# built documents.
+#
+# The short X.Y version.
+version = '0.1'
+# The full version, including alpha/beta/rc tags.
+release = '0.1'
+
+# The language for content autogenerated by Sphinx. Refer to documentation
+# for a list of supported languages.
+#language = None
+
+# There are two options for replacing |today|: either, you set today to some
+# non-false value, then it is used:
+#today = ''
+# Else, today_fmt is used as the format for a strftime call.
+#today_fmt = '%B %d, %Y'
+
+# List of patterns, relative to source directory, that match files and
+# directories to ignore when looking for source files.
+exclude_patterns = []
+
+# The reST default role (used for this markup: `text`) to use for all documents.
+#default_role = None
+
+# If true, '()' will be appended to :func: etc. cross-reference text.
+#add_function_parentheses = True
+
+# If true, the current module name will be prepended to all description
+# unit titles (such as .. function::).
+#add_module_names = True
+
+# If true, sectionauthor and moduleauthor directives will be shown in the
+# output. They are ignored by default.
+#show_authors = False
+
+# The name of the Pygments (syntax highlighting) style to use.
+pygments_style = 'sphinx'
+
+# A list of ignored prefixes for module index sorting.
+#modindex_common_prefix = []
+
+
+# -- Options for HTML output ---------------------------------------------------
+
+# The theme to use for HTML and HTML Help pages.  See the documentation for
+# a list of builtin themes.
+#html_theme = 'default'
+
+# Theme options are theme-specific and customize the look and feel of a theme
+# further.  For a list of options available for each theme, see the
+# documentation.
+#html_theme_options = {}
+
+# Add any paths that contain custom themes here, relative to this directory.
+#html_theme_path = []
+
+# The name for this set of Sphinx documents.  If None, it defaults to
+# "<project> v<release> documentation".
+#html_title = None
+
+# A shorter title for the navigation bar.  Default is the same as html_title.
+#html_short_title = None
+
+# The name of an image file (relative to this directory) to place at the top
+# of the sidebar.
+#html_logo = None
+
+# The name of an image file (within the static path) to use as favicon of the
+# docs.  This file should be a Windows icon file (.ico) being 16x16 or 32x32
+# pixels large.
+#html_favicon = None
+
+# Add any paths that contain custom static files (such as style sheets) here,
+# relative to this directory. They are copied after the builtin static files,
+# so a file named "default.css" will overwrite the builtin "default.css".
+html_static_path = ['_static']
+
+# If not '', a 'Last updated on:' timestamp is inserted at every page bottom,
+# using the given strftime format.
+#html_last_updated_fmt = '%b %d, %Y'
+
+# If true, SmartyPants will be used to convert quotes and dashes to
+# typographically correct entities.
+#html_use_smartypants = True
+
+# Custom sidebar templates, maps document names to template names.
+#html_sidebars = {}
+
+# Additional templates that should be rendered to pages, maps page names to
+# template names.
+#html_additional_pages = {}
+
+# If false, no module index is generated.
+#html_domain_indices = True
+
+# If false, no index is generated.
+#html_use_index = True
+
+# If true, the index is split into individual pages for each letter.
+#html_split_index = False
+
+# If true, links to the reST sources are added to the pages.
+#html_show_sourcelink = True
+
+# If true, "Created using Sphinx" is shown in the HTML footer. Default is True.
+#html_show_sphinx = True
+
+# If true, "(C) Copyright ..." is shown in the HTML footer. Default is True.
+#html_show_copyright = True
+
+# If true, an OpenSearch description file will be output, and all pages will
+# contain a <link> tag referring to it.  The value of this option must be the
+# base URL from which the finished HTML is served.
+#html_use_opensearch = ''
+
+# This is the file name suffix for HTML files (e.g. ".xhtml").
+#html_file_suffix = None
+
+# Output file base name for HTML help builder.
+htmlhelp_basename = 'SphericalGeometryToolkitdoc'
+
+
+# -- Options for LaTeX output --------------------------------------------------
+
+# The paper size ('letter' or 'a4').
+#latex_paper_size = 'letter'
+
+# The font size ('10pt', '11pt' or '12pt').
+#latex_font_size = '10pt'
+
+# Grouping the document tree into LaTeX files. List of tuples
+# (source start file, target name, title, author, documentclass [howto/manual]).
+latex_documents = [
+  ('index', 'SphericalGeometryToolkit.tex', u'Spherical Geometry Toolkit Documentation',
+   u'Michael Droettboom, STScI', 'manual'),
+]
+
+# The name of an image file (relative to this directory) to place at the top of
+# the title page.
+#latex_logo = None
+
+# For "manual" documents, if this is true, then toplevel headings are parts,
+# not chapters.
+#latex_use_parts = False
+
+# If true, show page references after internal links.
+#latex_show_pagerefs = False
+
+# If true, show URL addresses after external links.
+#latex_show_urls = False
+
+# Additional stuff for the LaTeX preamble.
+#latex_preamble = ''
+
+# Documents to append as an appendix to all manuals.
+#latex_appendices = []
+
+# If false, no module index is generated.
+#latex_domain_indices = True
+
+
+# -- Options for manual page output --------------------------------------------
+
+# One entry per manual page. List of tuples
+# (source start file, name, description, authors, manual section).
+man_pages = [
+    ('index', 'sphericalgeometrytoolkit', u'Spherical Geometry Toolkit Documentation',
+     [u'Michael Droettboom, STScI'], 1)
+]
+
+# If true, show URL addresses after external links.
+#man_show_urls = False
+
+
+# -- Options for Texinfo output ------------------------------------------------
+
+# Grouping the document tree into Texinfo files. List of tuples
+# (source start file, target name, title, author,
+#  dir menu entry, description, category)
+texinfo_documents = [
+  ('index', 'SphericalGeometryToolkit', u'Spherical Geometry Toolkit Documentation', u'Michael Droettboom, STScI',
+   'SphericalGeometryToolkit', 'One line description of project.', 'Miscellaneous'),
+]
+
+# Documents to append as an appendix to all manuals.
+#texinfo_appendices = []
+
+# If false, no module index is generated.
+#texinfo_domain_indices = True
+
+# How to display URL addresses: 'footnote', 'no', or 'inline'.
+#texinfo_show_urls = 'footnote'
+
+
+# Example configuration for intersphinx: refer to the Python standard library.
+intersphinx_mapping = {'http://docs.python.org/': None}
diff --git a/doc/source/cutlines.png b/doc/source/cutlines.png
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+++ b/doc/source/cutlines.png
diff --git a/doc/source/index.rst b/doc/source/index.rst
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+.. Spherical Geometry Toolkit documentation master file, created by
+   sphinx-quickstart on Tue Oct 11 09:04:48 2011.
+   You can adapt this file completely to your liking, but it should at least
+   contain the root `toctree` directive.
+
+Welcome to Spherical Geometry Toolkit's documentation!
+======================================================
+
+Contents:
+
+.. toctree::
+   :maxdepth: 2
+
+   user
+   api
+
+Indices and tables
+==================
+
+* :ref:`genindex`
+* :ref:`modindex`
+* :ref:`search`
+
diff --git a/doc/source/inside.png b/doc/source/inside.png
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+++ b/doc/source/inside.png
diff --git a/doc/source/user.rst b/doc/source/user.rst
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+User documentation
+==================
+
+.. currentmodule:: sphere
+
+The `sphere` library is a pure Python package for handling spherical
+polygons that represent arbitrary regions of the sky.
+
+Requirements
+------------
+
+- Python 2.7
+
+- Numpy 1.4 or later
+
+Coordinate representation
+-------------------------
+
+Coordinates in world space are traditionally represented by right
+ascension and declination (*ra* and *dec*), or longitude and latitude.
+While these representations are convenient, they have discontinuities
+at the poles, making operations on them trickier at arbitrary
+locations on the sky sphere.  Therefore, all internal operations of
+this library are done in 3D vector space, where coordinates are
+represented as (*x*, *y*, *z*) vectors.  The `sphere.vector` module
+contains functions to convert between (*ra*, *dec*) and (*x*, *y*,
+*z*) representations.
+
+While any (*x*, *y*, *z*) triple represents a vector and therefore a
+location on the sky sphere, a distinction must be made between
+normalized coordinates fall exactly on the unit sphere, and
+unnormalized coordinates which do not.  A normalized coordinate is
+defined as a vector whose length is 1, i.e.:
+
+.. math::
+
+    \sqrt{x^2 + y^2 + z^2} = 1
+
+To prevent unnecessary recomputation, many methods in this library
+assume that the vectors passed in are already normalized.  If this is
+not the case, `sphere.vector.normalize_vector` can be used to
+normalize an array of vectors.
+
+The library allows the user to work in either degrees or radians.  All
+methods that require or return an angular value have a `degrees`
+keyword argument.  When `degrees` is `True`, these measurements are in
+degrees, otherwise they are in radians.
+
+Spherical polygons
+------------------
+
+Spherical polygons are arbitrary areas on the sky sphere enclosed by
+great circle arcs.  They are represented by the
+`~sphere.polygon.SphericalPolygon` class.
+
+Representation
+``````````````
+
+The points defining the polygon are available from the
+`~polygon.SphericalPolygon.points` property.  It is a Nx3 array where
+each row is an (*x*, *y*, *z*) vector, normalized.  The polygon points
+are explicitly closed, i.e., the first and last points are the same.
+
+Where is the inside?
+^^^^^^^^^^^^^^^^^^^^
+
+The edges of a polygon serve to separate the “inside” from the
+“outside” area.  On a traditional 2D planar surface, the “inside” is
+defined as the finite area and the “outside” is the infinite area.
+However, since the surface of a sphere is cyclical, i.e., it wraps
+around on itself, the a spherical polygon actually defines two finite
+areas.  To specify which should be considered the “inside” vs. the
+“outside”, the definition of the polygon also has an “inside point”
+which is just any point that should be considered inside of the
+polygon.
+
+In the following image, the inside point (marked with the red dot)
+declares that the area of the polygon is the green region, and not the
+white region.
+
+.. image:: inside.png
+
+The inside point of the the polygon can be obtained from the
+`~polygon.SphericalPolygon.inside` property.
+
+Cut lines
+^^^^^^^^^
+
+If the polygon represents two disjoint areas or the polygon has holes,
+those areas will be connected by cut lines.  The following image shows
+a polygon made from the union of a number of cone areas which has both
+a hole and a disjoint region connected by cut lines.
+
+.. image:: cutlines.png
+
+Creating spherical polygons
+```````````````````````````
+
+.. currentmodule:: sphere.polygon
+
+`SphericalPolygon` objects have 4 different constructors:
+
+  - `SphericalPolygon`: Takes an array of (*x*, *y*, *z*)
+    points and an inside point.
+
+  - `SphericalPolygon.from_radec`: Takes an array of (*ra*, *dec*)
+    points and an inside point.
+
+  - `SphericalPolygon.from_cone`: Creates a polygon from a cone on the
+    sky shere.  Takes (*ra*, *dec*, *radius*).
+
+  - `SphericalPolygon.from_wcs`: Creates a polygon from the footprint
+    of a FITS image using its WCS header keywords.  Takes a FITS
+    filename or a `pyfits.Header` object.
+
+Operations on Spherical Polygons
+````````````````````````````````
+
+Once one has a `SphericalPolygon` object, there are a number of
+operations available:
+
+  - `~SphericalPolygon.contains_point`: Determines if the given point is inside the polygon.
+
+  - `~SphericalPolygon.intersects_poly`: Determines if one polygon intersects with another.
+
+  - `~SphericalPolygon.area`: Determine the area of a polygon.
+
+  - `~SphericalPolygon.union` and `~SphericalPolygon.multi_union`:
+    Return a new polygon that is the union of two or more polygons.
+
+  - `~SphericalPolygon.intersection` and
+    `~SphericalPolygon.multi_intersection`: Return a new polygon that
+    is the intersection of two or more polygons.
+
+  - `~SphericalPolygon.overlap`: Determine how much a given polygon
+    overlaps another.
+
+  - `~SphericalPolygon.draw`: Plots the polygon using matplotlib’s
+    Basemap toolkit.  This feature is rather bare and intended
+    primarily for debugging purposes.
+
+Great circle arcs
+-----------------
+
+.. currentmodule:: sphere.great_circle_arc
+
+As seen above, great circle arcs are used to define the edges of the
+polygon.  The `sphere.great_circle_arc` module contains a number of
+functions that are useful for dealing with them.
+
+- `length`: Returns the angular distance between two points on the sphere.
+
+- `intersection`: Returns the intersection point between two great
+  circle arcs.
+
+- `intersects`: Determines if two great circle arcs intersect.
+
+- `angle`: Calculate the angle between two great circle arcs.
+
+- `midpoint`: Calculate the midpoint along a great circle arc.