Sister cities

sc.md

Source: Sister Cities of the World + Graphviz

7158 18672 2463 731 0.7578 198 0.8743

• 7158 nodes
• 18672 edges
• 2463 connected components
• 731 strongly connected components
• 0.7578 fraction of nodes in a non-trivial strongly connected components
• 198 maximum degree
• 0.8743 fraction of non-tree edges

There are some minor issues with the data; some sister-city relationships are not hyperlinked, and links for cities with / in their name result in 404.

sc.sh

#!/bin/bash
wget -c -r -np en.sistercity.info
for i in en.sistercity.info/sister-cities/*.html; do
    xmllint --html --xpath '//div[@class="label"]/a/@href' "$i" 2>/dev/null |
    perl -Mre=/a -nE '
        sub escape { shift =~ s/([[:^graph:]])/sprintf "%%%02X", ord($1)/egr }
        sub unescape { shift =~ s/%([[:xdigit:]]{2})/chr(hex($1))/egr }
        BEGIN { say escape(shift), " -> {" }
        END { say "}" }
        say "\t" . escape(unescape($1)) while /href="(.*?)"/g
    ' "${i##*/}"
done |
perl -pE '
    BEGIN { say "digraph {" }
    END { say "$b [label=\"$a\"]" while ($a, $b) = each %id; say "}" }
    s%(\S*\w\S*)%$id{$1} //= "city" . ++$n%eg
' |
sccmap -sv