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我正在尝试结合两个教程/示例。 基本 choropleth 数据的动态更新

虽然我已经实现了来自人口普查 API 的数据更新并根据值更改地图颜色，但我无法将名称/值项添加到 SVG，这样如果您将鼠标悬停在map 它将显示 : 的工具提示。

从第一个示例中，我相信我需要的是：

.text(function(d) { return d.properties.name + ": " + data[pad(d.id)] + "%"; });

但是，当我添加它看起来像我应该去的地方时，我收到以下错误：

未捕获的类型错误：无法读取未定义的属性“名称”

这是我用来生成的代码：

function showData() {
    acsData = document.getElementById('measure').value;
    console.log('Gettting data for: ' + acsData);
    var jsonRequest = 'http://api.census.gov/data/2011/acs5?key=<mykey>&get=' + acsData + ',NAME&for=county:*&in=state:*';

    console.log(acsData);
    var dataSet = [];
    d3.json(jsonRequest, function (data) {
        $.each(data, function (key, val) {
            if (key > 0) {
                var apiValue = parseInt(val[0], 10);
                var apiState = val[2].toString();
                var apiCounty = val[3].toString();
                var elmentArray = [apiState, apiCounty, apiValue]
                dataSet.push(elmentArray);
                //console.log(elmentArray);
                //console.log(dataSet.length);
            }
        });

        var rateById = {};
        var maxVal; var minVal; var maxFips, minFips, maxCounty, minCounty;
        var vals = [];

        dataSet.forEach(function (d) {
            var fips = parseInt(d[0] + d[1], 10);
            //console.log(fips);
            if (fips !== 0 && fips.toString().substr(3) != '000') {
                var val = parseFloat(d[2], 10);
                if (val > maxVal || maxVal == null) { maxVal = val; maxFips = fips; }
                if (val < minVal || minVal == null) { minVal = val; minFips = fips; }
                rateById[fips] = +val;
                vals.push(val);
            }
        });
        countyFips.forEach(function (c) {
            if (parseInt(c.StateFips + c.CountyFips) == maxFips) maxCounty = c.CountyName + ', ' + c.State;
            if (parseInt(c.StateFips + c.CountyFips) == minFips) minCounty = c.CountyName + ', ' + c.State;
        });
        vals = vals.sort(d3.ascending);
        quantize = d3.scale.quantile()
        .domain(vals)
        .range(d3.range(20).map(function (i) {
            return color(i);
        }));

        mapSvg.select('g').selectAll('path')
        .transition()
        .duration(750)
        .style("fill", function (d) {
            return quantize(rateById[d.id]);
        });

        keySvg.select('g').remove();
        var keysEnter = keySvg.append('g').selectAll('circle')
                .data(d3.range(0, 21, 2))
                .enter();
        keysEnter
                .append('circle')
                .attr('cy', function (i) { return (i + 1) * 14; })
                .attr('cx', 12)
                .attr('r', 10)
                .style('fill', color);

        keysEnter
                .append('text')
                .attr('class', 'keyLabel')
                .attr('y', function (i) { return ((i + 1) * 14) + 5; })
                .attr('x', 26)
                .text(function (i) {
                    var keyLabel;
                    if (i == 0) keyLabel = d3.round(minVal || 0, 1) + ' ' + minCounty;
                    if (i != 0 && i != 20) keyLabel = d3.round(quantize.quantiles()[i], 1);
                    if (i == 20) keyLabel = d3.round(maxVal || 0, 1) + ' ' + maxCounty;
                    return keyLabel;
                });
    });
}
var containerWidth = 640,
                     baseWidth = 960,
                     baseStrokeWidth = 1,
                     scaleFactor = containerWidth / baseWidth;
function prepareMap() {
    mapSvg.append("g")
        .attr("class", "counties")
        .selectAll("path")
        .data(topojson.object(us, us.objects.counties).geometries)
        .enter().append("path")
        .style("fill", function (d) { return '#ccc' })
        .attr("d", path);

    mapSvg.append("path")
         .datum(topojson.mesh(us, us.objects.states, function (a, b) { return a.id !== b.id; }))
         .attr("class", "states")
         .attr("d", path)
         .append("svg:title")
         .text(function (d) { return d.properties.name + ": " + data[pad(d.id)] + "%"; });
}

function click(d) {
    var x = 0,
                y = 0,
                k = 1;

    if (d && centered !== d) {
        var centroid = path.centroid(d);
        x = -centroid[0] / 4;
        y = -centroid[1] / 4;
        k = 2;
        centered = d;
    } else {
        centered = null;
    }

    mapSvg.selectAll("path")
                .classed("active", centered && function (d) { return d === centered; });

    mapSvg.selectAll('g').transition()
                .duration(1000)
                .attr("transform", "scale(" + k + ")translate(" + x + "," + y + ")")
                .style("stroke-width", 1.5 / k + "px");
}

function ready(error, usData, countyFipsData) {
    us = usData;
    countyFips = countyFipsData;
    prepareMap();
    showData();
}
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