<?php
function getPoints() {
$data= "41.892694,-87.670898
42.056048,-88.000488
41.941744,-88.000488
42.072361,-88.209229
42.091933,-87.982635
42.149994,-88.133698
42.171371,-88.286133
42.23241,-88.305359
42.196811,-88.099365
42.189689,-88.188629
42.17646,-88.173523
42.180531,-88.209229
42.18168,-88.187943
42.185496,-88.166656
42.170485,-88.150864
42.150634,-88.140564
42.156743,-88.123741
42.118555,-88.105545
42.121356,-88.112755
42.115499,-88.102112
42.119319,-88.112411
42.118046,-88.110695
42.117791,-88.109322
42.182189,-88.182449
42.194145,-88.183823
42.189057,-88.196182
42.186513,-88.200645
42.180917,-88.197899
42.178881,-88.192062
41.881656,-87.6297
41.875521,-87.6297
41.87872,-87.636566
41.872073,-87.62661
41.868239,-87.634506
41.86875,-87.624893
41.883065,-87.62352
41.881021,-87.619743
41.879998,-87.620087
41.8915,-87.633476
41.875163,-87.620773
41.879125,-87.62558
41.862763,-87.608757
41.858672,-87.607899
41.865192,-87.615795
41.87005,-87.62043
42.073061,-87.973022
42.317241,-88.187256
42.272546,-88.088379
42.244086,-87.890625
42.044512,-88.28064
39.754977,-86.154785
39.754977,-89.648437
41.043369,-85.12207
43.050074,-89.406738
43.082179,-87.912598
42.7281,-84.572754
39.974226,-83.056641
38.888093,-77.01416
39.923692,-75.168457
40.794318,-73.959961
40.877439,-73.146973
40.611086,-73.740234
40.627764,-73.234863
41.784881,-71.367187
42.371988,-70.993652
35.224587,-80.793457
36.753465,-76.069336
39.263361,-76.530762
25.737127,-80.222168
26.644083,-81.958008
30.50223,-87.275391
29.436309,-98.525391
30.217839,-97.844238
29.742023,-95.361328
31.500409,-97.163086
32.691688,-96.877441
32.691688,-97.404785
35.095754,-106.655273
33.425138,-112.104492
32.873244,-117.114258
33.973545,-118.256836
33.681497,-117.905273
33.622982,-117.734985
33.741828,-118.092041
33.64585,-117.861328
33.700707,-118.015137
33.801189,-118.251343
33.513132,-117.740479
32.777244,-117.235107
32.707939,-117.158203
32.703317,-117.268066
32.610821,-117.075806
34.419726,-119.701538
37.750358,-122.431641
37.50673,-122.387695
37.174817,-121.904297
37.157307,-122.321777
37.271492,-122.033386
37.435238,-122.217407
37.687794,-122.415161
37.542025,-122.299805
37.609506,-122.398682
37.544203,-122.0224
37.422151,-122.13501
37.395971,-122.080078
45.485651,-122.739258
47.719463,-122.255859
47.303913,-122.607422
45.176713,-122.167969
39.566,-104.985352
39.124201,-94.614258
35.454518,-97.426758
38.473482,-90.175781
45.021612,-93.251953
42.417881,-83.056641
41.371141,-81.782227
33.791132,-84.331055
30.252543,-90.439453
37.421248,-122.174835
37.47794,-122.181702
37.510628,-122.254486
37.56943,-122.346497
37.593373,-122.384949
37.620571,-122.489319
36.984249,-122.03064
36.553017,-121.893311
36.654442,-121.772461
36.482381,-121.876831
36.15042,-121.651611
36.274518,-121.838379
37.817717,-119.569702
39.31657,-120.140991
38.933041,-119.992676
39.13785,-119.778442
39.108019,-120.239868
38.586082,-121.503296
38.723354,-121.289062
37.878444,-119.437866
37.782994,-119.470825
37.973771,-119.685059
39.001377,-120.17395
40.709076,-73.948975
40.846346,-73.861084
40.780452,-73.959961
40.778829,-73.958931
40.78372,-73.966012
40.783688,-73.965325
40.783692,-73.965615
40.783675,-73.965741
40.783835,-73.965873";
$linesdata = explode("\n", $data);
$coordinateArr= array();
foreach ($linesdata as $strpoint) {
$strpoint = explode(',',$strpoint);
$strpoint=array_map('floatval', $strpoint);
array_push($coordinateArr,$strpoint);
}
return $coordinateArr;
}
function halfMassRadius($coordinateArr) {
// tuning
$deltar = 0.1;
$massRatio = 0.2;
// init
$halfRMin = null;
$centroidKey = null;
$n=count($coordinateArr);
foreach ($coordinateArr as $i => $c) {
$radius = 0;
$stayHere = true;
# var_dump($c);
while ($stayHere) {
$radius = $radius + $deltar;
$nInside = count(getCoordinatesWithinRadius($coordinateArr,$c,$radius));
#print $c[0].' '.$c[1]. ' '.$radius.' '.$nInside. "\n";
if ($nInside >= $n*$massRatio) {
if (is_null($halfRMin) || $radius < $halfRMin) {
$halfRMin = $radius;
$centroidKey = $i;
}
$stayHere = false;
}
}
}
return $coordinateArr[$centroidKey][0] . ',' . $coordinateArr[$centroidKey][1];
}
function getCoordinatesWithinRadius ($coordinateArray, $center, $radius) {
$resultArray= array();
$lat1 = $center[0];
$long1 = $center[1];
foreach ($coordinateArray as $coordinate) {
$lat2 = $coordinate[0];
$long2 = $coordinate[1];
#$distance = 3959 * acos(cos(radians($lat1)) * cos(radians($lat2)) * cos(radians($long2) - radians($long1)) + sin(radians($lat1)) * sin(radians($lat2)));
$distance = acos(cos(radians($lat1)) * cos(radians($lat2)) * cos(radians($long2) - radians($long1)) + sin(radians($lat1)) * sin(radians($lat2)));
#$distance = asin(sqrt( pow(sin(radians($long2) - radians($long1)),2. )+ cos(radians($long2) ) ))
#$distance = pow(($lat1-$lat2),2.)+pow(($long1-$long2),2.);
if ($distance < $radius) array_push($resultArray, $coordinate);
}
return $resultArray;
}
function radians($deg) {
return $deg * M_PI / 180;
}
function main(){
print "beccato:\n";
$data=getPoints();
print halfMassRadius($data);
}
main();