How to generate geojson file ?

Hello,

I'd like to generate geojson file from GPS coordinates computed with Matlab.

here is an example of the expected geojson file:

{
  "type": "FeatureCollection",
  "features": [
    {
      "type": "Feature",
      "properties": {},
      "geometry": {
        "type": "Polygon",
        "coordinates": [
          [
            [
              -1.789,
              48.286
            ],
            [
              -1.781,
              48.283
            ],
            [
              -1.776,
              48.260
            ],
             ]

Using the below Matlab code, I could get correctly the first lines but I can't find how to generate the coordinates with the right syntax in the json file..

data.type='FeatureCollection';
data.features=[];
data.features.type = "Feature";
data.features.properties = "{}";
data.features.geometry.type = "LineString";
%data.features.geometry.coordinates = 
saveJSONfile(data, 'test2.json');

Thank for your help

[Carlos Vidal]

could you finally obtain the geoJSON? If not, I may come back with a solution later. Thank you.

[Dmitry Kaplan]

I am also interested in this. Would love to avoid a forest of sprintfs.

Answer 1

[Raphaël Nussbaumer]

Sadly Matlab is not really easy to use with such a popular and common format. Here is my solution for generating square polygon

FC={};
FC.type="FeatureCollection";
FC.features=[];
F={};
F.type='Feature';
F.geometry={};
F.properties={};
F.geometry.type="Polygon";
pos = cat(3,...
    loc(:,2)/10 + [0 res res 0 0],...
    loc(:,1)/10 + [0 0 res res 0]...
    );
res = 0.1;
for i=1:height(loc)
    F.geometry.coordinates(1,:,:)= pos(i,:,:);
    F.properties.value=0;
    FC.features=[FC.features;F];
end
fileID = fopen('grid.geojson','w');
fwrite(fileID,jsonencode(FC));
fclose(fileID)