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#!/opt/bin/perl |
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|
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=head1 NAME |
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|
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geo-latlon2place-makedb - generate database for use with Geo::LatLon2Place |
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|
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=head1 SYNOPSIS |
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|
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geo-latlon2place-makedb [OPTION]... inputfile.txt outputfile.cdb |
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|
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=head1 DESCRIPTION |
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|
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abc |
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|
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=head1 OPTIONS AND ARGUMENTS |
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|
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geo-latlon2place-makedb requires two arguments: a text file with geo data |
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and the name of the database file to be written. |
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|
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By default, the input file is considered to be in geonames gazetteer |
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format, but this can be customized using B<--extract>. |
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|
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=over |
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|
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=item B<--cellsize> km (default C<20>, or C<10> for geonames-postalcodes) |
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|
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The (minimum) size of a single grid cell in km - the data is binned into |
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cells of at least this size. It should not be larger than the search |
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radius. |
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|
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=item B<--extract> C<geonames>|C<geonames-postalcodes>|perl... |
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|
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The extraction method: the default is C<geonames>, which expects a |
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geonames database (L<https://download.geonames.org/export/dump/>, for |
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example F<DE.txt>, F<cities500.txt> or F<allCountries.txt>) and extracts |
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I<placename, countrycode> strings from it. |
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|
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The method C<geonames-postalcodes> does the same, but for a geonames |
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postal code database L<https://download.geonames.org/export/zip>, and |
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extracts C<zip name, countrycopde> strings. |
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|
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Lastly, you can specify a perl fragment that implements your own filtering |
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and extraction. |
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|
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=back |
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|
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=head1 FILTERING AND EXTRACTION |
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|
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Record selection and the returned data are not fixed - you can filter your records |
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yourself and associate any (reasonably short, the maximum is a bit above 200 octets) |
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binary blob with a coordinate pair. |
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|
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To do this, you have to provide a perl fragment that extracts latitude, |
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longitude, a weight and the associated data blob from an input line stored |
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in C<$_>. The file is opened using the C<:perlio> layer, so if your input |
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file is in UTF-8, so will be C<$_>. |
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|
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For example, the following would expect an input file with space separated |
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latitude, longitude, weight and name, where name can contain spaces, which |
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is useful when you want to provide your own input data: |
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|
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geo-latlon2place-makedb --extract 'chomp; split / /, 4' input output |
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|
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A slighly more verbose example expecting only latitude, longitude and a |
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name would be: |
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|
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geo-latlon2place-makedb --extract ' |
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chomp; |
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my ($lat, $lon, $name) = split / /, 4; |
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($lat, $lon, 1, $name) |
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' input output |
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|
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If you want to skip certain lines without adding anything to the database, |
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you can return nothing: |
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|
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geo-latlon2place-makedb --extract ' |
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chomp; |
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my ($lat, $lon, $name) = split / /; |
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return unless $lat < 0; # only add southern hemisphere points |
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($lat, $lon, 1, $name) |
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' input output |
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|
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In general, the fragment should return either an empty list, or a |
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four-tuple with decimal latitude, longitude, a weight (integer 0..255) |
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and the binary data to be associated with the coordinate. Other than the |
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weight, these should be self-explaining. The weight is used during search |
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and will be multiplied to the square of the distance, and is used to make |
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larger cities win over small ones when the coordinate is somewhere between |
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them. |
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|
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The standard extractors (C<geonames> and C<geonames-postalcodes>) provide |
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a UTF-8-encoded string as blob, but any binary data will do, for example, |
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if you want to associate your coordinate pairs with some short-ish |
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integer codes, you could do this: |
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|
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geo-latlon2place-makedb --extract ' |
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chomp; |
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my ($lat, $lon, $id) = split / /, 4; |
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($lat, $lon, 1, pack "w", $id) |
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' input output |
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|
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And later use C<unpack "w"> on the data returned by C<lookup>. |
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|
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The C<geonames> filter looks similar to the following fragment, which |
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shows off some more filtering possibilities: |
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|
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my ($id, $name, undef, undef, $lat, $lon, $t1, $t2, $cc, undef, $a1, $s2, $a3, $a4, $pop, undef) = split /\t/; |
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return if $t1 ne "P"; # only places |
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# minimum population 200, or it is a populated place with no known population |
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$pop => 200 |
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or ($pop eq "" and $t2 eq "PPL") |
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or return; |
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|
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# skip certain places we are not interested in |
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return if $t2 eq "PPLX"; # section of populated place |
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return if $t2 eq "PPLW"; # destroyed populated place |
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return if $t2 eq "PPLH"; # historical populated place |
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return if $t2 eq "PPLQ"; # abandoned populated place |
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|
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# geonames has a lot of very long place names which aren't |
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# actually place names, so ignore very long names |
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60 > length $name |
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or return; |
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|
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# we estimate a weight by dividing 25 by the radius of the place, |
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# which we get by assuming a fixed population density of 5000 # people |
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# per square km, # which is almost always a considerable over-estimate. |
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# 25 and 5000 are pretty much made-up, feel free to improve and |
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# send me the results. |
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my $w = 25 / (1 + sqrt $pop / 5000); |
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|
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# administrative centers get a fixed low weight |
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if ($t2 =~ /^PPLA(\d*)/) { |
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$w = $1 || 1; |
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} |
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|
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($lat, $lon, $w, "$name, $cc") |
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|
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=head1 AUTHOR |
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|
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Marc Lehmann <schmorp@schmorp.de> |
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|
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=cut |
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use common::sense; |
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use Getopt::Long; |
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use Geo::LatLon2Place (); |
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use Pod::Usage (); |
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|
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GetOptions |
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"help|h" => sub { Pod::Usage::pod2usage -exittval => 0, verbose => 1 }, |
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"extract=s" => \my $extract, |
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"cellsize=i" => \my $km, |
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or Pod::Usage::pod2usage |
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-exitval => 1, |
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; |
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@ARGV == 2 |
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or die "need exactly two paths: inputfile.txt outputdatabase.cdb\n"; |
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$extract ||= "geonames"; |
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|
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if ($extract eq "geonames") { |
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$extract = sub { |
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my ($id, $name, undef, undef, $lat, $lon, $t1, $t2, $cc, undef, $a1, $s2, $a3, $a4, $pop, undef) = split /\t/; |
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return if $t1 ne "P"; # only places |
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$pop => 200 |
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or ($pop eq "" and $t2 eq "PPL") |
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or return; |
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|
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return if $t2 eq "PPLX"; # section of populated place |
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return if $t2 eq "PPLW"; # destroyed populated place |
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return if $t2 eq "PPLH"; # historical populated place |
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return if $t2 eq "PPLQ"; # abandoned populated place |
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|
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# geonames has a lot of very long place names which aren't |
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# actually place names, so ignore very long names |
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60 > length $name |
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or return; |
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|
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my $w = 25 / (1 + sqrt $pop / 5000); |
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if ($t2 =~ /^PPLA(\d+)/) { |
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$w = $1 || 1; |
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} |
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($lat, $lon, $w, "$name, $cc") |
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}; |
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} elsif ($extract eq "geonames-postalcodes") { |
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$km ||= 10; |
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$extract = sub { |
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my ($cc, $zip, $name, undef, undef, undef, undef, undef, undef, $lat, $lon, undef) = split /\t/; |
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|
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# https://buttermaidbakery.com/pages/what-is-an-apo-fpo-dpo-address |
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return if $name =~ /^[AFD]PO [A-Z][A-Z]\z/ and $cc eq "US"; |
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($lat, $lon, 1, "$zip $name, $cc") |
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}; |
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} else { |
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$extract = eval "#line 1 \"extract fragment\"\nsub { $extract; }"; |
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die "$@" if $@; |
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} |
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$km ||= 20; |
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my $torad = (atan2 1,0) / 90; |
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my $boxes = int 6378 * 2 * 2 * (atan2 1,0) / $km; # equator radius / cell size |
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open my $fh, "<:perlio", $ARGV[0] |
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or die "$ARGV[0]: $!\n"; |
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my @grid; |
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|
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while (<$fh>) { |
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my ($lat, $lon, $w, $payload) = $extract->() |
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or next; |
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|
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unless (255 >= length $payload) { |
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$payload =~ s/([^(\x20-\x7e])/sprintf "\\x%02x", ord $1/ge; |
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warn "payload too long, skipping: $payload\n"; |
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next; |
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} |
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my $blat = int $boxes * cos $lat * $torad; # can be 0, but does not matter |
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my $x = int (($lon + 180) * $blat / 360); |
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my $y = int (($lat + 90) * $boxes / 180); |
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|
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# we use 16 bit for lat/lon, 8 bi8t for the weight, BER-id, counted name and CC |
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push @{ $grid[$y][$x] }, pack "s< s< C C/a*", $lat * 32767 / 90, $lon * 32767 / 180, $w, $payload; |
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} |
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############################################################################# |
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# write gridded data out |
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|
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open my $cdb, ">", $ARGV[1] |
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or die "$ARGV[1]: $!\n"; |
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Geo::LatLon2Place::cdb_make_start fileno $cdb |
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and die "cdb_make_start failure"; |
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|
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Geo::LatLon2Place::cdb_make_add "", pack "a4VVVV", "SRGL", 2, $km, $boxes, time; |
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|
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############################################################################# |
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# now we walk the grid using a hilbert curve to increase locality when querying |
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|
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my ($max, $sum, $cnt); # statistics |
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|
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my ($x, $y) = (-1, 0); |
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|
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sub step { # move one step into $_[0] direction: 0 x++, 1 y++, 2 x--, 3 y-- |
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($_[0] & 1 ? $y : $x) += 1 - ($_[0] & 2); |
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|
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# write cell at $x,$y, if any |
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my $c = $grid[$y][$x] |
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or return; |
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|
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undef $grid[$y][$x]; # for paranoia check |
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|
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# statistics |
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$sum += scalar @$c; |
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$cnt++; |
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$max = [(scalar @$c), $x, $y] if @$c > $max->[0]; |
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|
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Geo::LatLon2Place::cdb_make_add |
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+(pack "s< s<", $x, $y), |
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+(join "", @$c) |
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and "cdb_make_add failure"; |
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} |
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|
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sub hilbert; |
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sub hilbert { # order dir rot |
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my $order = $_[0] >> 1 |
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or return; |
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|
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hilbert $order, $_[1] + $_[2], -$_[2]; step $_[1] + $_[2]; |
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hilbert $order, $_[1] , $_[2]; step $_[1] ; |
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hilbert $order, $_[1] , $_[2]; step $_[1] - $_[2]; |
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hilbert $order, $_[1] - $_[2], -$_[2]; |
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} |
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step 0; # move to 0,0 |
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hilbert @grid * 2, 0, 1; |
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|
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# paranoia-check, make sure we wrote out all cells |
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for (@grid) { |
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grep $_, @$_ |
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and die; |
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} |
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|
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############################################################################# |
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|
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Geo::LatLon2Place::cdb_make_finish |
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and die "cdb_make_finish failed"; |
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close $cdb; |
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|
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$max->[2] = $max->[2] * 180 / $boxes - 90; |
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my $blat = int $boxes * cos $max->[2] * $torad; |
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$max->[1] = $max->[1] * 360 / $blat - 180; |
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print "cell size: $km km, grid size: $boxes, non-empty cell count: $cnt\naverage cell size: ", int $sum/$cnt, ", maximum cell size: $max->[0] (at $max->[2] $max->[1])\n"; |
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|
