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Algorithm

How does wiki-evolution generate the visualization.

Revisions log

A. First we ask API for some basic wiki statistics.

siteinfo provides the following metrics:

  • sitename
  • number of pages
  • number of edits

Mostlinkedcategories will give us the list of the biggest categories. It will be used to generate a "virtual path" for each article in revision log. value field threshold is calculated as 2% * (number of pages).

B. Get all revisions for all pages

Pages list API

Page's revisions API

Each revision is tagged with:

  • the type of a contribution: (A)dded, (M)odified or (D)eleted
  • virtual path: the list of categories the current page is in is taken, using the list of the biggest categories the list of N categories "generates" the virtual path followed by the article name: e.g. Countries/Europe/Nordic Countries/Iceland. The list is kept in order to generate a tree-like structure when visualized.
  • color: the max_edits_per_page value is calculated using site statistics (see point A) = number of edits / number of pages. Then the color is calculated using the following formula: white with alpha( max( 1, max_edits_per_page / current_page_edits_so_far ) ) (with alpha in between 0 and 1). The more active (the more edited) the article is the brighter it appears on the visualization. The new articles are displayed as blue, removed as red.

C. Generate the custom log for gource

<UNIX timestamp>|<author>|<(A)dded, (M)odified or (D)eleted>|<"virtual path" + article name>|<color>

1275543595|andrew|M|Countries/Europe/Nordic Countries/Iceland|FF0000

Visualization

#!/bin/sh

resolution=1360x720
seconds_per_day=0.01
auto_skip_seconds=0.1
elasticity=0.05
output=gource.mp4

wiki-evolution --wiki <PATH TO api.php> | xvfb-run -a -s "-screen 0 $resolutionx24" gource \
  --log-format custom - \
  --seconds-per-day $seconds_per_day \
  --auto-skip-seconds $auto_skip_seconds \
  --elasticity $elasticity \
  --multi-sampling --stop-at-end -b 000000  --hide filenames,dirnames,progress,mouse --user-friction .2 \
  --background-image background.png --logo  wiki_logo.png --user-image-dir $wikiname/avatars \
  -$resolution \
  -o - | ffmpeg -y -r 60 -f image2pipe -vcodec ppm -i - \
  -vcodec libx264 -preset ultrafast -pix_fmt yuv420p -crf 1 -threads 0 -bf 0 $output