diff options
Diffstat (limited to 'tagging/utils.py')
| -rw-r--r-- | tagging/utils.py | 388 |
1 files changed, 248 insertions, 140 deletions
diff --git a/tagging/utils.py b/tagging/utils.py index af50bac..9bfd07f 100644 --- a/tagging/utils.py +++ b/tagging/utils.py @@ -1,140 +1,248 @@ -import math -import re -import types - -from django.db.models.query import QuerySet -from django.utils.encoding import force_unicode, smart_unicode - -# Python 2.3 compatibility -if not hasattr(__builtins__, 'set'): - from sets import Set as set - -find_tag_re = re.compile(r'[-\w]+', re.U) - -def get_tag_name_list(tag_names): - """ - Finds tag names in the given string and return them as a list. - """ - if tag_names is not None: - tag_names = force_unicode(tag_names) - results = find_tag_re.findall(tag_names or '') - return results - -def get_tag_list(tags): - """ - Utility function for accepting tag input in a flexible manner. - - If a ``Tag`` object is given, it will be returned in a list as - its single occupant. - - If given, the tag names in the following will be used to create a - ``Tag`` ``QuerySet``: - - * A string, which may contain multiple tag names. - * A list or tuple of strings corresponding to tag names. - * A list or tuple of integers corresponding to tag ids. - - If given, the following will be returned as-is: - - * A list or tuple of ``Tag`` objects. - * A ``Tag`` ``QuerySet``. - """ - from tagging.models import Tag - if isinstance(tags, Tag): - return [tags] - elif isinstance(tags, QuerySet) and tags.model is Tag: - return tags - elif isinstance(tags, types.StringTypes): - return Tag.objects.filter(name__in=get_tag_name_list(tags)) - elif isinstance(tags, (types.ListType, types.TupleType)): - if len(tags) == 0: - return tags - contents = set() - for item in tags: - if isinstance(item, types.StringTypes): - contents.add('string') - elif isinstance(item, Tag): - contents.add('tag') - elif isinstance(item, (types.IntType, types.LongType)): - contents.add('int') - if len(contents) == 1: - if 'string' in contents: - return Tag.objects.filter(name__in=[smart_unicode(tag) \ - for tag in tags]) - elif 'tag' in contents: - return tags - elif 'int' in contents: - return Tag.objects.filter(id__in=tags) - else: - raise ValueError(u'If a list or tuple of tags is provided, they must all be tag names, Tag objects or Tag ids.') - else: - raise ValueError(u'The tag input given was invalid.') - -def get_tag(tag): - """ - Utility function for accepting single tag input in a flexible - manner. - - If a ``Tag`` object is given it will be returned as-is; if a - string or integer are given, they will be used to lookup the - appropriate ``Tag``. - - If no matching tag can be found, ``None`` will be returned. - """ - from tagging.models import Tag - if isinstance(tag, Tag): - return tag - - try: - if isinstance(tag, types.StringTypes): - return Tag.objects.get(name=tag) - elif isinstance(tag, (types.IntType, types.LongType)): - return Tag.objects.get(id=tag) - except Tag.DoesNotExist: - pass - - return None - -# Font size distribution algorithms -LOGARITHMIC, LINEAR = 1, 2 - -def calculate_cloud(tags, steps=4, distribution=LOGARITHMIC): - """ - Add a ``font_size`` attribute to each tag according to the - frequency of its use, as indicated by its ``count`` - attribute. - - ``steps`` defines the range of font sizes - ``font_size`` will - be an integer between 1 and ``steps`` (inclusive). - - ``distribution`` defines the type of font size distribution - algorithm which will be used - logarithmic or linear. It must be - either ``tagging.utils.LOGARITHMIC`` or ``tagging.utils.LINEAR``. - - The algorithm to scale the tags logarithmically is from a - blog post by Anders Pearson, 'Scaling tag clouds': - http://thraxil.com/users/anders/posts/2005/12/13/scaling-tag-clouds/ - """ - if len(tags) > 0: - thresholds = [] - counts = [tag.count for tag in tags] - max_weight = float(max(counts)) - min_weight = float(min(counts)) - - # Set up the appropriate thresholds - if distribution == LOGARITHMIC: - thresholds = [math.pow(max_weight - min_weight + 1, float(i) / float(steps)) \ - for i in range(1, steps + 1)] - elif distribution == LINEAR: - delta = (max_weight - min_weight) / float(steps) - thresholds = [min_weight + i * delta for i in range(1, steps + 1)] - else: - raise ValueError(u'Invalid font size distribution algorithm specified: %s.' % distribution) - - for tag in tags: - font_set = False - for i in range(steps): - if not font_set and tag.count <= thresholds[i]: - tag.font_size = i + 1 - font_set = True - return tags +"""
+Tagging utilities - from user tag input parsing to tag cloud
+calculation.
+"""
+import math
+import types
+
+from django.db.models.query import QuerySet
+from django.utils.encoding import force_unicode
+from django.utils.translation import ugettext as _
+
+# Python 2.3 compatibility
+if not hasattr(__builtins__, 'set'):
+ from sets import Set as set
+
+def parse_tag_input(input):
+ """
+ Parses tag input, with multiple word input being activated and
+ delineated by commas and double quotes. Quotes take precedence, so
+ they may contain commas.
+
+ Returns a sorted list of unique tag names.
+ """
+ if not input:
+ return []
+
+ input = force_unicode(input)
+
+ # Special case - if there are no commas or double quotes in the
+ # input, we don't *do* a recall... I mean, we know we only need to
+ # split on spaces.
+ if u',' not in input and u'"' not in input:
+ words = list(set(split_strip(input, u' ')))
+ words.sort()
+ return words
+
+ words = []
+ buffer = []
+ # Defer splitting of non-quoted sections until we know if there are
+ # any unquoted commas.
+ to_be_split = []
+ saw_loose_comma = False
+ open_quote = False
+ i = iter(input)
+ try:
+ while 1:
+ c = i.next()
+ if c == u'"':
+ if buffer:
+ to_be_split.append(u''.join(buffer))
+ buffer = []
+ # Find the matching quote
+ open_quote = True
+ c = i.next()
+ while c != u'"':
+ buffer.append(c)
+ c = i.next()
+ if buffer:
+ word = u''.join(buffer).strip()
+ if word:
+ words.append(word)
+ buffer = []
+ open_quote = False
+ else:
+ if not saw_loose_comma and c == u',':
+ saw_loose_comma = True
+ buffer.append(c)
+ except StopIteration:
+ # If we were parsing an open quote which was never closed treat
+ # the buffer as unquoted.
+ if buffer:
+ if open_quote and u',' in buffer:
+ saw_loose_comma = True
+ to_be_split.append(u''.join(buffer))
+ if to_be_split:
+ if saw_loose_comma:
+ delimiter = u','
+ else:
+ delimiter = u' '
+ for chunk in to_be_split:
+ words.extend(split_strip(chunk, delimiter))
+ words = list(set(words))
+ words.sort()
+ return words
+
+def split_strip(input, delimiter=u','):
+ """
+ Splits ``input`` on ``delimiter``, stripping each resulting string
+ and returning a list of non-empty strings.
+ """
+ if not input:
+ return []
+
+ words = [w.strip() for w in input.split(delimiter)]
+ return [w for w in words if w]
+
+def edit_string_for_tags(tags):
+ """
+ Given list of ``Tag`` instances, creates a string representation of
+ the list suitable for editing by the user, such that submitting the
+ given string representation back without changing it will give the
+ same list of tags.
+
+ Tag names which contain commas will be double quoted.
+
+ If any tag name which isn't being quoted contains whitespace, the
+ resulting string of tag names will be comma-delimited, otherwise
+ it will be space-delimited.
+ """
+ names = []
+ use_commas = False
+ for tag in tags:
+ name = tag.name
+ if u',' in name:
+ names.append('"%s"' % name)
+ continue
+ elif u' ' in name:
+ if not use_commas:
+ use_commas = True
+ names.append(name)
+ if use_commas:
+ glue = u', '
+ else:
+ glue = u' '
+ return glue.join(names)
+
+def get_tag_list(tags):
+ """
+ Utility function for accepting tag input in a flexible manner.
+
+ If a ``Tag`` object is given, it will be returned in a list as
+ its single occupant.
+
+ If given, the tag names in the following will be used to create a
+ ``Tag`` ``QuerySet``:
+
+ * A string, which may contain multiple tag names.
+ * A list or tuple of strings corresponding to tag names.
+ * A list or tuple of integers corresponding to tag ids.
+
+ If given, the following will be returned as-is:
+
+ * A list or tuple of ``Tag`` objects.
+ * A ``Tag`` ``QuerySet``.
+
+ """
+ from tagging.models import Tag
+ if isinstance(tags, Tag):
+ return [tags]
+ elif isinstance(tags, QuerySet) and tags.model is Tag:
+ return tags
+ elif isinstance(tags, types.StringTypes):
+ return Tag.objects.filter(name__in=parse_tag_input(tags))
+ elif isinstance(tags, (types.ListType, types.TupleType)):
+ if len(tags) == 0:
+ return tags
+ contents = set()
+ for item in tags:
+ if isinstance(item, types.StringTypes):
+ contents.add('string')
+ elif isinstance(item, Tag):
+ contents.add('tag')
+ elif isinstance(item, (types.IntType, types.LongType)):
+ contents.add('int')
+ if len(contents) == 1:
+ if 'string' in contents:
+ return Tag.objects.filter(name__in=[force_unicode(tag) \
+ for tag in tags])
+ elif 'tag' in contents:
+ return tags
+ elif 'int' in contents:
+ return Tag.objects.filter(id__in=tags)
+ else:
+ raise ValueError(_('If a list or tuple of tags is provided, they must all be tag names, Tag objects or Tag ids.'))
+ else:
+ raise ValueError(_('The tag input given was invalid.'))
+
+def get_tag(tag):
+ """
+ Utility function for accepting single tag input in a flexible
+ manner.
+
+ If a ``Tag`` object is given it will be returned as-is; if a
+ string or integer are given, they will be used to lookup the
+ appropriate ``Tag``.
+
+ If no matching tag can be found, ``None`` will be returned.
+ """
+ from tagging.models import Tag
+ if isinstance(tag, Tag):
+ return tag
+
+ try:
+ if isinstance(tag, types.StringTypes):
+ return Tag.objects.get(name=tag)
+ elif isinstance(tag, (types.IntType, types.LongType)):
+ return Tag.objects.get(id=tag)
+ except Tag.DoesNotExist:
+ pass
+
+ return None
+
+# Font size distribution algorithms
+LOGARITHMIC, LINEAR = 1, 2
+
+def _calculate_thresholds(min_weight, max_weight, steps):
+ delta = (max_weight - min_weight) / float(steps)
+ return [min_weight + i * delta for i in range(1, steps + 1)]
+
+def _calculate_tag_weight(weight, max_weight, distribution):
+ """
+ Logarithmic tag weight calculation is based on code from the
+ `Tag Cloud`_ plugin for Mephisto, by Sven Fuchs.
+
+ .. _`Tag Cloud`: http://www.artweb-design.de/projects/mephisto-plugin-tag-cloud
+ """
+ if distribution == LINEAR or max_weight == 1:
+ return weight
+ elif distribution == LOGARITHMIC:
+ return math.log(weight) * max_weight / math.log(max_weight)
+ raise ValueError(_('Invalid distribution algorithm specified: %s.') % distribution)
+
+def calculate_cloud(tags, steps=4, distribution=LOGARITHMIC):
+ """
+ Add a ``font_size`` attribute to each tag according to the
+ frequency of its use, as indicated by its ``count``
+ attribute.
+
+ ``steps`` defines the range of font sizes - ``font_size`` will
+ be an integer between 1 and ``steps`` (inclusive).
+
+ ``distribution`` defines the type of font size distribution
+ algorithm which will be used - logarithmic or linear. It must be
+ one of ``tagging.utils.LOGARITHMIC`` or ``tagging.utils.LINEAR``.
+ """
+ if len(tags) > 0:
+ counts = [tag.count for tag in tags]
+ min_weight = float(min(counts))
+ max_weight = float(max(counts))
+ thresholds = _calculate_thresholds(min_weight, max_weight, steps)
+ for tag in tags:
+ font_set = False
+ tag_weight = _calculate_tag_weight(tag.count, max_weight, distribution)
+ for i in range(steps):
+ if not font_set and tag_weight <= thresholds[i]:
+ tag.font_size = i + 1
+ font_set = True
+ return tags
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