Ajuste o script do google earth engine a seguir para que o grafico de pizza mostre a porcentagem de área em hectares de cada uma das bandas. Aqui está o exemplo de script: Map.setOptions("SATELLITE")// "ROADMAP", "SATELLITE", "HYBRID" or "TERRAIN"

var veredasmapbiomasfreq = ee.FeatureCollection("users/maximomenezesgee/Otto_4_Urucuia_mapbiomas_veredas_Union2");
var arenizacao = ee.FeatureCollection("users/maximomenezesgee/Otto_4_Urucuia_Landsat_Union_arenizacao3");

var mascara1 = ee.Image(100).toInt().clip(veredasmapbiomasfreq)

var mascara2 = ee.Image(200).toInt().clip(arenizacao)

var mascara3 = ee.Image([mascara2,mascara1])
.reduce(ee.Reducer.firstNonNull())

var verd_areniz1 = ee.Image("users/maximomenezesgee/campo_arenizacao_landsat_doutorado_raster")
.select('arenizacao_count')
.updateMask(mascara3)

var verd_areniz = ee.Image(400).toInt().updateMask(verd_areniz1)

var imagebands1 = ee.Image([
mascara3.updateMask(mascara3.eq(100).rename('vereda')), 
mascara3.updateMask(mascara3.eq(200).rename('arenizacao'))
])

var mascara4 = ee.Image([verd_areniz, mascara1])
.reduce(ee.Reducer.firstNonNull())

var imagebands2 = ee.Image([
mascara4.updateMask(mascara4.eq(100).rename('vereda')), 
mascara4.updateMask(mascara4.eq(400).rename('freq_arenizacao'))
])


Map.addLayer(verd_areniz1,{min:1,max:50,//min:0,max:0.4,
  palette: 
//['#FF0000','#FF7F00','#FFFF00', '#00FF00', '#0000FF', '#4B0082', '#9400D3'],
['#9400D3','#4B0082','#0000FF', '#00FF00', '#FFFF00', '#FF7F00', '#FF0000']
},'verd_areniz');

Map.addLayer(mascara3,{min:1,max:200, palette: 
//['#FF0000','#FF7F00','#FFFF00', '#00FF00', '#0000FF', '#4B0082', '#9400D3']},
['#9400D3','#4B0082','#0000FF', '#00FF00', '#FFFF00', '#FF7F00', '#FF0000']},
'Vereda_Arenizacao', null, 0.4);

var chart1 = ui.Chart.image.regions({
                  image: imagebands1.selfMask(),
                  regions: geometry,
                  reducer: ee.Reducer.sum(),
                  scale: 30,
                  seriesProperty: 'label',
                  //xLabels: monthNames
                })
                .setChartType('PieChart')//'PieChart')//ColumnChart
                .setOptions({
                  title: 'Porcentagem arenização',
                  colors:
                    //['#FF0000','#FF7F00','#FFFF00', '#00FF00', '#0000FF', '#4B0082', '#9400D3'],
                    //['#9400D3', '#4B0082', '#0000FF', '#00FF00', '#FFFF00', '#FF7F00', '#FF0000'],
                    ['#FF0000', '#00FF00'],
                });
print(chart1);

var chart2 = ui.Chart.image.regions({
                  image: imagebands2.selfMask(),
                  regions: geometry,
                  reducer: ee.Reducer.sum(),
                  scale: 30,
                  seriesProperty: 'label',
                  //xLabels: monthNames
                })
                .setChartType('PieChart')//'PieChart')//ColumnChart
                .setOptions({
                  title: 'Porcentagem arenização (frequência)',
                  colors:
                    //['#FF0000','#FF7F00','#FFFF00', '#00FF00', '#0000FF', '#4B0082', '#9400D3'],
                    //['#9400D3', '#4B0082', '#0000FF', '#00FF00', '#FFFF00', '#FF7F00', '#FF0000'],
                    ['#FF0000', '#00FF00'],
                });
print(chart2);