How to fetch Google Ngrams data

fetch-ngrams-data.pl

my $url = URI->new('http://books.google.com/ngrams/graph');

$url->query_form(
  year_start => 1800,
  year_end => 2000,
  corpus => $corpus,
  smoothing => 30,
  content => encode_utf8($q),
);

my $res = $ua->get($url, accept_encoding => 'deflate,gzip');
my $s = $res->decoded_content(charset => 'none');

my ($year_from, $year_to) = $s =~ /drawD3Chart\(data, (\d+), (\d+)/;
my $duration = $year_to - $year_from;

$s =~ s/.*var data =//s;
$s =~ s/\];.*/]/s;
my $d = eval { JSON->new->decode($s) };