Blogofile tag cloud filter

tag_cloud.py

import blogofile_bf as bf
import math

# A Blogofile based tag cloud with linear distribution.
# This works for either tags or categories.
# Ryan McGuire - www.blogofile.com

# Usage:
# In your template, add the following:
#   ${bf.filter.run_chain("tag_cloud","categories")}
# or
#   ${bf.filter.run_chain("tag_cloud","tags")}

tag_cloud = None
category_cloud = None

#Posts -- where to get the posts from?
# bf.posts in 0.6
# bf.blog.posts in 0.7+
posts = bf.posts

def run(content):
    divisions = 6
    global tag_cloud, category_cloud
    if content == "categories":
        if category_cloud is None:
            category_cloud = build_cloud("categories", divisions)
        return category_cloud_to_html(category_cloud)
    if content == "tags":
        if tag_cloud is None:
            tag_cloud = build_cloud("tags", divisions)
        return tag_cloud_to_html(tag_cloud)

def category_cloud_to_html(cloud):
    html = ["<div id='tag_cloud'>"]
    for category in sorted(cloud):
        size = cloud[category]
        link = category.path
        html.append("<a href='%(link)s' class='size_%(size)s'>%(category)s</a>" % locals())
    html.append("</div>")
    return "\n".join(html)

def tag_cloud_to_html(cloud):
    #TODO: make the links actually go to a tag controller
    html = ["<div id='tag_cloud'>"]
    for tag in sorted(cloud):
        size = cloud[tag]
        html.append("<a href='/tag/' class='size_%(size)s'>%(tag)s</a>" % locals())
    html.append("</div>")
    return "\n".join(html)

def build_cloud(cloud_type, divisions):
    cloud = {}
    #Count the tag hits
    tag_counts = {}
    for post in posts:
        for tag in getattr(post, cloud_type):
            tag_counts[tag] = tag_counts.get(tag,0) + 1
    #Divide the range from the minimum tag count to the maximum tag count into
    #(divisions) font sizes. This is done linearly, if you have disparate tag
    #counts, you might want to use a logarithmic distribution.
    max_t = max(tag_counts.values())
    min_t = min(tag_counts.values())
    dist = float(max_t - min_t) / (divisions - 1)
    i = min_t
    ranges = []
    while i<=max_t:
        r = (i, i+dist)
        i += dist
        ranges.append(r)
    #Put the tags in the right bins
    for tag, tag_n in tag_counts.items():
        bin = 0
        for r_min,r_max in ranges:
            if tag_n >= r_min and tag_n < r_max:
                cloud[tag] = bin
            bin += 1
    return cloud

tag_style.css

#tag_cloud .size_5 {
    font-size: 2.75em;
}
#tag_cloud .size_4 {
    font-size: 2.4em;
}
#tag_cloud .size_3 {
    font-size: 2.05em;
}
#tag_cloud .size_2 {
    font-size: 1.7em;
}
#tag_cloud .size_1 {
    font-size: 1.35em;
}
#tag_cloud .size_0 {
    font-size: 1.0em;
}