FeatureCollection 簡介

相關地圖項目群組可結合為 FeatureCollection,以便對整個集合執行其他作業,例如篩選、排序和算繪。除了簡單的特徵 (幾何圖形 + 屬性) 之外,地圖集合也可以包含其他集合。

FeatureCollection 建構函式

建立 FeatureCollection 的方法之一,是向建構函式提供功能清單。地圖項目不必具有相同的幾何圖形類型或屬性。例如:

程式碼編輯器 (JavaScript)

// Make a list of Features.
var features = [
  ee.Feature(ee.Geometry.Rectangle(30.01, 59.80, 30.59, 60.15), {name: 'Voronoi'}),
  ee.Feature(ee.Geometry.Point(-73.96, 40.781), {name: 'Thiessen'}),
  ee.Feature(ee.Geometry.Point(6.4806, 50.8012), {name: 'Dirichlet'})
];

// Create a FeatureCollection from the list and print it.
var fromList = ee.FeatureCollection(features);
print(fromList);

Python 設定

請參閱「 Python 環境」頁面,瞭解 Python API 和如何使用 geemap 進行互動式開發。

import ee
import geemap.core as geemap

Colab (Python)

# Make a list of Features.
features = [
    ee.Feature(
        ee.Geometry.Rectangle(30.01, 59.80, 30.59, 60.15), {'name': 'Voronoi'}
    ),
    ee.Feature(ee.Geometry.Point(-73.96, 40.781), {'name': 'Thiessen'}),
    ee.Feature(ee.Geometry.Point(6.4806, 50.8012), {'name': 'Dirichlet'}),
]

# Create a FeatureCollection from the list and print it.
from_list = ee.FeatureCollection(features)
display(from_list)

個別幾何圖形也可以轉換為單一 FeatureFeatureCollection

程式碼編輯器 (JavaScript)

// Create a FeatureCollection from a single geometry and print it.
var fromGeom = ee.FeatureCollection(ee.Geometry.Point(16.37, 48.225));
print(fromGeom);

Python 設定

請參閱「 Python 環境」頁面,瞭解 Python API 和如何使用 geemap 進行互動式開發。

import ee
import geemap.core as geemap

Colab (Python)

# Create a FeatureCollection from a single geometry and print it.
from_geom = ee.FeatureCollection(ee.Geometry.Point(16.37, 48.225))
display(from_geom)

表格資料集

Earth Engine 會代管各種表格資料集。如要載入資料表資料集,請將資料表 ID 提供給 FeatureCollection 建構函式。例如,如要載入 RESOLVE 生態區資料:

程式碼編輯器 (JavaScript)

var fc = ee.FeatureCollection('RESOLVE/ECOREGIONS/2017');
Map.setCenter(12.17, 20.96, 3);
Map.addLayer(fc, {}, 'ecoregions');

Python 設定

請參閱「 Python 環境」頁面,瞭解 Python API 和如何使用 geemap 進行互動式開發。

import ee
import geemap.core as geemap

Colab (Python)

fc = ee.FeatureCollection('RESOLVE/ECOREGIONS/2017')
m = geemap.Map()
m.set_center(12.17, 20.96, 3)
m.add_layer(fc, {}, 'ecoregions')
display(m)

請注意,您可以透過 Earth Engine 資料目錄搜尋圖像資料集和表格資料集。

隨機樣本

如要取得指定區域內的隨機點集合,您可以使用:

程式碼編輯器 (JavaScript)

// Define an arbitrary region in which to compute random points.
var region = ee.Geometry.Rectangle(-119.224, 34.669, -99.536, 50.064);

// Create 1000 random points in the region.
var randomPoints = ee.FeatureCollection.randomPoints(region);

// Display the points.
Map.centerObject(randomPoints);
Map.addLayer(randomPoints, {}, 'random points');

Python 設定

請參閱「 Python 環境」頁面,瞭解 Python API 和如何使用 geemap 進行互動式開發。

import ee
import geemap.core as geemap

Colab (Python)

# Define an arbitrary region in which to compute random points.
region = ee.Geometry.Rectangle(-119.224, 34.669, -99.536, 50.064)

# Create 1000 random points in the region.
random_points = ee.FeatureCollection.randomPoints(region)

# Display the points.
m = geemap.Map()
m.center_object(random_points)
m.add_layer(random_points, {}, 'random points')
display(m)