# Copyright (C) 2011 Anurag Priyam - MIT License | |
module Jekyll | |
# Jekyll plugin to generate tag clouds. | |
# | |
# The plugin defines a `tag_cloud` tag that is rendered by Liquid into a tag | |
# cloud: | |
# | |
# <div class='cloud'> | |
# {% tag_cloud %} | |
# </div> | |
# | |
# The tag cloud itself is a collection of anchor tags, styled dynamically | |
# with the `font-size` CSS property. The range of values, and unit to use for | |
# `font-size` can be specified with a very simple syntax: | |
# | |
# {% tag_cloud font-size: 16 - 28px %} | |
# | |
# The output is automatically formatted to use the same number of decimal | |
# places as used in the argument: | |
# | |
# {% tag_cloud font-size: 0.8 - 1.8em %} # => 1 | |
# {% tag_cloud font-size: 0.80 - 1.80em %} # => 2 | |
# | |
# Tags that have been used less than a certain number of times can be | |
# filtered out from the tag cloud with the optional `threshold` parameter: | |
# | |
# {% tag_cloud threshold: 2%} | |
# | |
# Both the parameters can be easily clubbed together: | |
# | |
# {% tag_cloud font-size: 50 - 150%, threshold: 2%} | |
# | |
# The plugin randomizes the order of tags every time the cloud is generated. | |
class TagCloud < Liquid::Tag | |
safe = true | |
# tag cloud variables - these are setup in `initialize` | |
attr_reader :size_min, :size_max, :precision, :unit, :threshold | |
def initialize(name, params, tokens) | |
# initialize default values | |
@size_min, @size_max, @precision, @unit = 70, 170, 0, '%' | |
@threshold = 1 | |
# process parameters | |
@params = Hash[*params.split(/(?:: *)|(?:, *)/)] | |
process_font_size(@params['font-size']) | |
process_threshold(@params['threshold']) | |
super | |
end | |
def render(context) | |
# get an Array of [tag name, tag count] pairs | |
count = context.registers[:site].tags.map do |name, posts| | |
[name, posts.count] if posts.count >= threshold | |
end | |
# clear nils if any | |
count.compact! | |
# get the minimum, and maximum tag count | |
min, max = count.map(&:last).minmax | |
# map: [[tag name, tag count]] -> [[tag name, tag weight]] | |
weight = count.map do |name, count| | |
# logarithmic distribution | |
weight = (Math.log(count) - Math.log(min))/(Math.log(max) - Math.log(min)) | |
[name, weight] | |
end | |
# shuffle the [tag name, tag weight] pairs | |
weight.sort_by! { rand } | |
# reduce the Array of [tag name, tag weight] pairs to HTML | |
weight.reduce("") do |html, tag| | |
name, weight = tag | |
size = size_min + ((size_max - size_min) * weight).to_f | |
size = sprintf("%.#{@precision}f", size) | |
html << "<a style='font-size: #{size}#{unit}' href='/tags.html##{name}'>#{name}</a>\n" | |
end | |
end | |
private | |
def process_font_size(param) | |
/(\d*\.{0,1}(\d*)) *- *(\d*\.{0,1}(\d*)) *(%|em|px)/.match(param) do |m| | |
@size_min = m[1].to_f | |
@size_max = m[3].to_f | |
@precision = [m[2].size, m[4].size].max | |
@unit = m[5] | |
end | |
end | |
def process_threshold(param) | |
/\d*/.match(param) do |m| | |
@threshold = m[0].to_i | |
end | |
end | |
end | |
end | |
Liquid::Template.register_tag('tag_cloud', Jekyll::TagCloud) |
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Thanks! Could you please add an option that allows me to sort the tags alphabetically? I think it's disturbing when the site always looks different. By now, I've commented |
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I've replaced line 82 by
This gives absolutee links to tag pages. But it also shows How could we create the tag cloud once and only insert the generated HTML where needed? |
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Break this into two plugins: a generator plugin instead and a filter plugin (See the Jekyll documentation on writing plugins). The generator will run first and only once, construct a hash containing all the data you need to make the tag cloud (e.g name, weight pairs). Then you can define filter tag as you do above, but just have it read the hash from the generator rather than constructing the data. |
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For sorting the tags alphabetically, switching: |
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What is i have to write in _config.yml file to start it? Just my second day with Jekyll so i full of love as well as chaos in fact)) |
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Thanks for this! This works great for the tag cloud on my jekyll-based blog.