openlayers 3 ol.proj.transform is converting dynamic geolocation points to zero

Question

I am trying to use an example from stackoverflow to insert dynamic data into map using openlayers 3.* . the problem is : the code is running OK when I insert the numbers direct to the statement like this:

 geometry: new ol.geom.Point(ol.proj.transform([-72.0704,46.678],'EPSG:4326','EPSG:3857')),

but when I tried to simulate json data as the following code: then some magic happened :

• When substituting only the longitude I got the marker on the right location,
• When substituting only the latitude then the latitude will be converted to zero,

• When substituting longitude and latitude, the marker will not show up.

   function AddMarkers() { var iconFeatures=[]; data = [{"longitude":"-72.0704","latitude":"46.678"},{"longitude":"-73.1234","latitude":"45.678"},{"longitude":"46.738586","latitude":"24.774265"}]; var iconFeature = new ol.Feature({ geometry: new ol.geom.Point(ol.proj.transform([data[0].longitude,46.678], 'EPSG:4326', 'EPSG:3857')), name: 'Null Island', population: 4000, rainfall: 500 }); var iconFeature1 = new ol.Feature({ geometry: new ol.geom.Point(ol.proj.transform([28.7753927 , data[1].latitude], 'EPSG:4326', 'EPSG:3857')), name: 'Null Island Two', population: 4001, rainfall: 501 }); var iconFeature2 = new ol.Feature({ geometry: new ol.geom.Point(ol.proj.transform([data[2].longitude,data[2].latitude], 'EPSG:4326', 'EPSG:3857')), name: 'Null Island Two', population: 4002, rainfall: 502 }); iconFeatures.push(iconFeature); iconFeatures.push(iconFeature1); iconFeatures.push(iconFeature2); var vectorSource = new ol.source.Vector({ features: iconFeatures //add an array of features }); var iconStyle = new ol.style.Style({ image: new ol.style.Icon(/** @type {olx.style.IconOptions} */ ({ anchor: [0.5, 46], anchorXUnits: 'fraction', anchorYUnits: 'pixels', opacity: 0.75, src: 'images/icon.png' })) }); var vectorLayer = new ol.layer.Vector({ source: vectorSource, style: iconStyle }); return vectorLayer; 

  }

So, why this magic happened only when using data from a json array, but is not happening when the numbers inserted directlty to the statement.

Answer 1

我正在使用php json编码json_encode（）并在数据中添加引号，因此从经度和纬度值中删除（修剪）引号。