javascript - 从 geojson 获取最大值和最小值

Question

我有一个 geojson 文件，我想从特定字段获取最大值和最小值。这是我的 geojson 文件:

var commune = {"type": "FeatureCollection","features": [{ 
        "type": "Feature",
        "id":"", 
        "properties": 
        { 
            "nom":"Ain (01)",
            "CODE_DEPT":"01", 
            "MARIE_2007":"242937", 
            "CELIB_2007":"150068", 
            "VEUF_2007":"31475", 
            "DIVOR_2007":"32177",
            "MARIE_2011":"248332", 
            "CELIB_2011":"162880", 
            "VEUF_2011":"32059", 
            "DIVOR_2011":"36617",
            "P11_POP":"603827",
            "P07_POP":"574391",
            "NAIS12":"7242",
            "NAIS11":"7265",
            "DECE12":"4577",
            "DECE11":"4305",
            "ENCTOT11":"4329",
            "ENCTOT10":"4828",
            "ENNTOT11":"27186" 
        }, 
        "geometry": { 
            "type": "Polygon", 
            "coordinates": [[ [4.92452011,45.80404],[4.91857895,45.8093526],[4.91976994,45.82948887],[4.933601220000001,46.51245471000001],[4.93475135,46.51332864000001],[4.94725813,46.51446477999999],[4.94737243,46.50843994000001],[4.95280079,46.50448051],[4.96265289,46.5065581],[4.970033120000001,46.51410222],[4.98021847,46.51520743],[5.006366140000001,46.50970907],[5.01059281,46.51107719],[5.01244901,46.50297671],[5.01424122,46.50045988000001],[5.05090592,46.48625806],[5.0547548,46.4842847],[5.06721345,46.48577781],[5.07144999,46.48582009],[5.09526702,46.49798349],[5.112817620000001,46.49296539],[5.85065585,46.26170731],[5.86085144,46.26877548000001],[5.867698190000001,46.26822003],[5.86918965,46.26498538000001],[5.89197324,46.28359891000002],[5.89462537,46.28661469],[5.909195170000001,46.28394973],[5.91592224,46.29281579000001],[5.91892961,46.30930141],[5.9259046,46.31377309],[5.93732476,46.30977235000001],[5.94152708,46.30926953],[5.94401041,46.31220679],[5.97513797,46.35030159000001],[5.984121710000001,46.36265843],[6.01338356,46.37599880000001],[6.031020600000001,46.38810776],[6.052803630000001,46.41141842],[6.06057745,46.41751374],[6.0640057,46.41623036],[6.09777972,46.40858757000001],[5.01668616,45.80561526],[5.0122926,45.80523386],[5.00120298,45.81012438],[4.996959160000001,45.80914469],[4.99291668,45.80780002000001],[4.980338380000001,45.80584619],[4.97037128,45.80738551],[4.96692373,45.80904157],[4.951514780000001,45.80877107],[4.94683539,45.80941096],[4.92452011,45.80404] ]] 
            } 
        }, { 
        "type": "Feature",
        "id":"", 
        "properties": 
        { 
            "nom":"Allier (03)",
            "CODE_DEPT":"03", 
            "MARIE_2007":"142567", 
            "CELIB_2007":"94352", 
            "VEUF_2007":"30977", 
            "DIVOR_2007":"22520",
            "MARIE_2011":"136735", 
            "CELIB_2011":"97444", 
            "VEUF_2011":"30224", 
            "DIVOR_2011":"24318",
            "P11_POP":"342729",
            "P07_POP":"343124",
            "NAIS12":"3288",
            "NAIS11":"3196",
            "DECE12":"4346",
            "DECE11":"4221",
            "ENCTOT11":"1934",
            "ENCTOT10":"2311",
            "ENNTOT11":"15148" 
        }, 
        "geometry": { 
            "type": "Polygon", 
            "coordinates": [[ [3.77334923,46.22719224],[3.78504663,46.22044738],[3.793573530000001,46.20769509],[3.78865075,46.19803992],[3.78979534,46.18748797],[3.803437390000001,46.16864814000001],[3.80973786,46.16310508000001],[3.80631061,46.16135084],[3.791626770000001,46.15659053000001],[3.79005403,46.15339828],[3.80126092,46.13143229],[3.79348746,46.112203],[3.80283828,46.11013932],[3.81835242,46.09301073],[3.82129095,46.0902456],[3.81658482,46.08456626000001],[3.81820687,46.07803905],[3.80561326,46.05306164000001],[3.80754254,46.04977906],[3.81587514,46.01910220000001],[3.82470625,46.00660501],[3.82733464,46.00021645000001],[3.83207127,45.99966784],[3.831742450000001,45.99944723],[3.82820481,45.99708246],[3.823224290000001,45.98815868],[3.80971781,45.98466361000001],[3.805150300000001,45.98329332],[3.781716630000001,45.97278891],[3.76002135,45.98068649],[3.75521038,45.97982028000001],[3.75064829,45.97003337],[3.742083070000001,45.9666941],[3.70961012,45.97413986000001],[3.70179941,45.96573133],[3.70450027,45.95554857],[3.69416443,45.94816809],[3.01428986,46.10527975],[3.00897068,46.11451573],[2.99427508,46.12320352],[2.980135230000001,46.12452646000001],[2.97175641,46.12169378],[2.96870044,46.12383515],[2.96440126,46.1290685],[2.96162502,46.13185592],[2.95213046,46.17133301000001],[2.94832477,46.1691754],[2.915704579999999,46.17413433],[2.913346020000001,46.17645055],[2.91076592,46.17865808],[2.919069420000001,46.18241252],[2.91992196,46.18947185],[2.91214414,46.20252971000001],[2.915816280000001,46.21278583],[2.923872110000001,46.21709903],[2.93274196,46.21868123000001],[2.93635804,46.22090247],[2.93912319,46.22374893000001],[2.93228017,46.23231447],[2.94598622,46.24167975],[2.94125766,46.24208205],[2.92590548,46.24938855000001],[2.90571884,46.24872598000001],[2.886322980000001,46.2531322],[2.86601825,46.25107846],[2.85976804,46.25659574000001],[2.85530571,46.25518568],[2.819168900000001,46.24179544],[2.819100750000001,46.23848478],[2.81768315,46.23211183],[2.5980228,46.59546224],[2.58332169,46.59434333],[2.57766143,46.60700494],[2.56839,46.60939027],[2.57292466,46.61045161000001],[2.58866016,46.61695059],[2.58593117,46.61976268],[2.58460338,46.62637012],[2.59632897,46.63672549999999],[2.59310888,46.64658424999999],[2.5890008,46.64809584],[2.56700624,46.65248768000001],[2.57056311,46.65927302000001],[2.606155,46.66930708],[2.60703665,46.6626474],[2.62392751,46.65663147000001],[2.63157087,46.66880445000001],[2.63185212,46.67221260000001],[2.62164231,46.67927395],[2.62348625,46.68930971000001],[2.62822321,46.69031437],[2.648089880000001,46.68895750000002],[2.65619177,46.69735612],[2.67426887,46.70227942],[2.67780141,46.7046171],[2.67617951,46.71083867],[2.6886199,46.72118332],[2.70316089,46.7222083],[2.70525376,46.7356157],[2.70484521,46.73903576],[2.73065122,46.74800057000001],[2.73453852,46.74622377],[2.74380344,46.73055578],[2.75512498,46.72392033],[2.758528720000001,46.71766317],[2.77137721,46.72126778],[2.7747598,46.7189517],[2.78275538,46.72246554],[2.79341957,46.73356149],[2.82257668,46.7354207],[2.827496070000001,46.73533674],[2.84117422,46.72732408000001],[2.84573507,46.72662012000001],[2.84382406,46.73923313000001],[2.8446387,46.7423694],[2.87535324,46.76064543],[2.88042249,46.77003211],[2.89434484,46.77417565],[2.89896986,46.77567349000001],[2.91093521,46.78135406],[2.90892388,46.78447702],[2.912953410000001,46.79019676],[2.93610446,46.79539505],[2.93989199,46.79318895],[2.94438298,46.79299427],[2.95250127,46.79269000000001],[2.95992679,46.80387786000001],[2.97990239,46.80342556],[2.99660733,46.79696079000001],[3.01615045,46.79984158000001],[3.027596990000001,46.79337813000001],[3.03207072,46.79491561],[3.03626634,46.77596958000002],[3.03754839,46.77283891],[3.04955339,46.75772189],[3.07961559,46.73996855],[3.875371550000001,46.27254662],[3.86891928,46.26367132],[3.85055547,46.26209134],[3.8456955,46.26181420000001],[3.80760052,46.25740175],[3.802695,46.23851437],[3.79880443,46.23991442000001],[3.778241490000001,46.24305742000001],[3.77332368,46.24247199],[3.76928843,46.24042644],[3.77334923,46.22719224] ]] 
            } 
        }, { 
        "type": "Feature",
        "id":"", 
        "properties": 
        { 
            "nom":"Alpes-de-Haute Provence (04)",
            "CODE_DEPT":"04", 
            "MARIE_2007":"64195", 
            "CELIB_2007":"41983", 
            "VEUF_2007":"11250", 
            "DIVOR_2007":"11881",
            "MARIE_2011":"64385", 
            "CELIB_2011":"45210", 
            "VEUF_2011":"11200", 
            "DIVOR_2011":"13050",
            "P11_POP":"160959",
            "P07_POP":"156071",
            "NAIS12":"1561",
            "NAIS11":"1578",
            "DECE12":"1674",
            "DECE11":"1657",
            "ENCTOT11":"1688",
            "ENCTOT10":"1854",
            "ENNTOT11":"11459"
        }, 
        "geometry": { 
            "type": "Polygon", 
            "coordinates": [[ 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]] 
            }}]};

如果您有任何输入来获取“P11_POP”字段的最大值和最小值，这将非常有帮助。

我已经尝试过这个功能，但我一定错过了一些东西:

function getMax(commune, prop) {
 var max;
        for (var i=0 ; i<commune.length ; i++) {
            if (!max || parseInt(commune[i][prop]) > parseInt(max[prop]))
                max = commune[i];
        }
        return max;
    }
    var maxPpg = getMax(commune.features.properties, "P11_POP");
    console.log(maxPpg.nom);

谢谢

Answer 1

这里存在很多问题(特别是 Adrian May 指出的问题)。我重写了该函数，以便您了解如何修复它。然而，由于硬编码的“属性”字符串，它不再是通用函数。为了更简单，我还使用了 Math.max 函数:

function getMax(commune, prop) {
    var max = -10000000;
    for (var i=0 ; i<commune.length ; i++) {
        max = Math.max(parseInt(commune[i]["properties"][prop]), max);
    }
    return max;
}
var maxPpg = getMax(commune.features, "P11_POP");
alert(maxPpg);