MODISFiltering

var srtm = ee.Image("CGIAR/SRTM90_V4"),
    pt = /* color: #d63000 */ee.Geometry.Point([-94.05706782341004, 43.65432823960525]),
    modis = ee.ImageCollection("MODIS/006/MOD09GA");

var oeel=require('users/OEEL/lib:loadAll');


// only 2020
modis=modis.filterDate('2020-10-01','2021-01-01');
print(modis.first());

print(ui.Chart.image.series(modis.select('sur_ref.*'), pt, ee.Reducer.mean(), 1000));
// remove cloud
modis=modis.map(function(im){return im.updateMask(im.select('state_1km').bitwiseAnd(3).not());});
print(ui.Chart.image.series(modis.select('sur_ref.*'), pt, ee.Reducer.mean(), 1000));
modis=modis.map(oeel.Algorithms.MODIS.terrainShadow({dem:srtm}))
      .map(function(im){return im.updateMask(im.select('shadowMask').not());});
      
print(modis.first());
print(ui.Chart.image.series(modis.select('sur_ref.*'), pt, ee.Reducer.mean(), 1000));

// interpolate between data and smooth out
modis=oeel.ImageCollection.SavatskyGolayFilter(modis,
        ee.Filter.maxDifference(1000*3600*24*15, 'system:time_start', null, 'system:time_start'),
        function(infromedImage,estimationImage){
          return ee.Image.constant(ee.Number(infromedImage.get('system:time_start'))
            .subtract(ee.Number(estimationImage.get('system:time_start'))));},
        5,['sur_refl_b.*']);
        
print(modis);
        
print('Smoothed data',ui.Chart.image.series(modis.select('d_0_sur_ref.*'), pt, ee.Reducer.mean(), 1000));

print('Smoothed derivate',ui.Chart.image.series(modis.select('d_1_sur_ref.*'), pt, ee.Reducer.mean(), 1000));

print('list of functions used',oeel.refs());