Distance and Bearing: Difference between revisions

=={{header|Raku}}==

<syntaxhighlight lang="raku" line>use Text::CSV;

constant $EARTH_RADIUS_IN_NAUTICAL_MILES = 6372.8 / 1.852;

sub degrees ( Real $rad ) { $rad / tau * 360 }

sub radians ( Real $deg ) { $deg * tau / 360 }

sub haversine ( Real $x ) { ($x / 2).sin.² }

sub arc_haver ( Real $x ) { $x.sqrt.asin * 2 }

sub great_circle_distance ( \φ1, \λ1, \φ2, \λ2 ) {

# https://en.wikipedia.org/wiki/Haversine_formula

# latitude (represented by φ) and longitude (represented by λ)

# hav(θ) = hav(φ₂ − φ₁) + cos(φ₁) cos(φ₂) hav(λ₂ − λ₁)

arc_haver(

haversine(φ2 - φ1)

+ haversine(λ2 - λ1) * cos(φ1) * cos(φ2)

);

}

sub great_circle_bearing ( \φ1, \λ1, \φ2, \λ2 ) {

atan2( φ2.cos * (λ2 - λ1).sin,

φ1.cos * φ2.sin - φ1.sin * φ2.cos * (λ2 - λ1).cos,

);

}

sub distance_and_bearing ( $lat1, $lon1, $lat2, $lon2 ) {

my @ll = map &radians, $lat1, $lon1, $lat2, $lon2;

my $dist = great_circle_distance(|@ll);

my $theta = great_circle_bearing( |@ll);

return $dist * $EARTH_RADIUS_IN_NAUTICAL_MILES,

degrees( $theta + (tau if $theta < 0) )

}

sub find_nearest_airports ( $latitude, $longitude, $csv_path ) {

my &d_and_b_from_here = &distance_and_bearing.assuming($latitude, $longitude);

my @airports = csv(

in => $csv_path,

headers => [<ID Name City Country IATA ICAO Latitude Longitude>],

);

for @airports -> %row {

%row<Distance Bearing> = d_and_b_from_here( +%row<Latitude>, +%row<Longitude> );

}

return @airports.sort(*.<Distance>);

}

sub MAIN ( $lat = 51.514669, $long = 2.198581, $wanted = 20, $csv = 'airports.dat' ) {

printf "%7s\t%7s\t%-7s\t%-15s\t%s\n", <Dist Bear ICAO Country Name>;

for find_nearest_airports($lat, $long, $csv).head($wanted) {

printf "%7.1f\t %03d\t%-7s\t%-15s\t%s\n",

.<Distance Bearing ICAO Country Name>;

}

}</syntaxhighlight>

{{out}}

<pre>

Dist Bear ICAO Country Name

30.7 146 EBFN Belgium Koksijde Air Base

31.3 127 EBOS Belgium Ostend-Bruges International Airport

33.6 252 EGMH United Kingdom Kent International Airport

34.4 195 LFAC France Calais-Dunkerque Airport

42.6 105 EBKW Belgium Westkapelle heliport

51.6 240 EGMK United Kingdom Lympne Airport

52.8 114 EBUL Belgium Ursel Air Base

56.2 274 EGMC United Kingdom Southend Airport

56.4 162 LFQT France Merville-Calonne Airport

56.5 137 EBKT Belgium Wevelgem Airport

57.3 089 EHMZ Netherlands Midden-Zeeland Airport

58.0 235 EGMD United Kingdom Lydd Airport

59.0 309 EGUW United Kingdom RAF Wattisham

59.3 339 EGSM United Kingdom Beccles Airport

59.7 146 LFQO France Lille/Marcq-en-Baroeul Airport

62.2 250 EGKH United Kingdom Lashenden (Headcorn) Airfield

63.7 200 LFAT France Le Touquet-Côte d'Opale Airport

64.2 261 EGTO United Kingdom Rochester Airport

66.3 149 LFQQ France Lille-Lesquin Airport

68.4 271 EGMT United Kingdom Thurrock Airfield</pre>