rebaseline_server: create ImagePairSet-- holds a number of ImagePairs to examine

gm/rebaseline_server/imagepairset.py

Index: gm/rebaseline_server/imagepairset.py
diff --git a/gm/rebaseline_server/imagepairset.py b/gm/rebaseline_server/imagepairset.py
new file mode 100644
index 0000000000000000000000000000000000000000..6bfaeeda8ce611728145c96fa66f5135e30e6e9a
--- /dev/null
+++ b/gm/rebaseline_server/imagepairset.py
@@ -0,0 +1,124 @@
+#!/usr/bin/python
+
+"""
+Copyright 2014 Google Inc.
+
+Use of this source code is governed by a BSD-style license that can be
+found in the LICENSE file.
+
+ImagePairSet class; see its docstring below.
+"""
+
+import column
+
+# Keys used within dictionary representation of ImagePairSet.
+KEY__COLUMNHEADERS = 'columnHeaders'
+KEY__IMAGEPAIRS = 'imagePairs'
+KEY__IMAGESETS = 'imageSets'
+KEY__IMAGESETS__BASE_URL = 'baseUrl'
+KEY__IMAGESETS__DESCRIPTION = 'description'
+
+DEFAULT_DESCRIPTIONS = ('setA', 'setB')
+
+
+class ImagePairSet(object):
+  """A collection of ImagePairs, representing two arbitrary sets of images.
+
+  These could be:
+  - images generated before and after a code patch
+  - expected and actual images for some tests
+  - or any other pairwise set of images.
+  """
+
+  def __init__(self, descriptions=None):
+    """
+    Args:
+      descriptions: a (string, string) tuple describing the two image sets.
+          If not specified, DEFAULT_DESCRIPTIONS will be used.
+    """
+    self._column_header_factories = {}
+    self._descriptions = descriptions or DEFAULT_DESCRIPTIONS
+    self._extra_column_tallies = {}  # maps column_id -> values
+                                     #                -> instances_per_value
+    self._image_pair_dicts = []
+
+  def add_image_pair(self, image_pair):
+    """Adds an ImagePair; this may be repeated any number of times.

[rmistry, 2014/02/13 12:10:02]

Another style comment (last one I promise). I have typically seen comments like
this when they are used in a single line:

"""One line comment here."""

I have not seen much of:

"""One line comment here.
"""

(It makes the file one line larger).

I found http://www.python.org/dev/peps/pep-0257/#one-line-docstrings that is
referred to in the style guide, looks like they are using:
"""One line comment."""

[epoger, 2014/02/13 17:16:31]

Done throughout.  Makes sense.

+    """
+    # Special handling when we add the first ImagePair...
+    if not self._image_pair_dicts:
+      self._base_url = image_pair.base_url
+
+    if image_pair.base_url != self._base_url:
+      raise Exception('added ImagePair with base_url "%s" instead of "%s"' % (
+          image_pair.base_url, self._base_url))
+    self._image_pair_dicts.append(image_pair.as_dict())
+    extra_columns_dict = image_pair.extra_columns_dict
+    if extra_columns_dict:
+      for column_id, value in extra_columns_dict.iteritems():
+        self._add_extra_column_entry(column_id, value)
+
+  def set_column_header_factory(self, column_id, column_header_factory):
+    """Overrides the default settings for one of the extraColumn headers.
+
+    Args:
+      column_id: string; unique ID of this column (must match a key within
+          an ImagePair's extra_columns dictionary)
+      column_header_factory: a ColumnHeaderFactory object
+    """
+    self._column_header_factories[column_id] = column_header_factory
+
+  def get_column_header_factory(self, column_id):
+    """Returns the ColumnHeaderFactory object for a particular extraColumn.
+
+    Args:
+      column_id: string; unique ID of this column (must match a key within
+          an ImagePair's extra_columns dictionary)
+    """
+    column_header_factory = self._column_header_factories.get(column_id, None)
+    if not column_header_factory:
+      column_header_factory = column.ColumnHeaderFactory(header_text=column_id)
+      self._column_header_factories[column_id] = column_header_factory
+    return column_header_factory
+
+  def _add_extra_column_entry(self, column_id, value):
+    """Records one column_id/value extraColumns pair found within an ImagePair.
+
+    We use this information to generate tallies within the column header
+    (how many instances we saw of a particular value, within a particular
+    extraColumn).
+    """
+    known_values_for_column = self._extra_column_tallies.get(column_id, None)
+    if not known_values_for_column:
+      known_values_for_column = {}
+      self._extra_column_tallies[column_id] = known_values_for_column
+    instances_of_this_value = known_values_for_column.get(value, 0)
+    instances_of_this_value += 1
+    known_values_for_column[value] = instances_of_this_value
+
+  def _column_headers_as_dict(self):
+    """Returns all column headers as a dictionary.
+    """
+    asdict = {}
+    for column_id, values_for_column in self._extra_column_tallies.iteritems():
+      column_header_factory = self.get_column_header_factory(column_id)
+      asdict[column_id] = column_header_factory.create_as_dict(
+          values_for_column)
+    return asdict
+
+  def as_dict(self):
+    """Returns a dictionary describing this package of ImagePairs.
+
+    Uses the KEY__* constants as keys.
+    """
+    return {
+        KEY__COLUMNHEADERS: self._column_headers_as_dict(),
+        KEY__IMAGEPAIRS: self._image_pair_dicts,
+        KEY__IMAGESETS: [{
+            KEY__IMAGESETS__BASE_URL: self._base_url,
+            KEY__IMAGESETS__DESCRIPTION: self._descriptions[0],
+        }, {
+            KEY__IMAGESETS__BASE_URL: self._base_url,
+            KEY__IMAGESETS__DESCRIPTION: self._descriptions[1],
+        }],
+    }