Pengumuman: Semua project nonkomersial yang terdaftar untuk menggunakan Earth Engine sebelum
15 April 2025 harus
memverifikasi kelayakan nonkomersial untuk mempertahankan akses Earth Engine.
ee.Dictionary.map
Tetap teratur dengan koleksi
Simpan dan kategorikan konten berdasarkan preferensi Anda.
Memetakan algoritma ke kamus. Algoritma diharapkan menggunakan 2 argumen, kunci dari kamus yang ada dan nilai yang sesuai, serta menampilkan nilai baru untuk kunci yang diberikan. Jika algoritma menampilkan null, kunci akan dihapus.
| Penggunaan | Hasil |
|---|
Dictionary.map(baseAlgorithm) | Kamus |
| Argumen | Jenis | Detail |
|---|
ini: dictionary | Kamus | |
baseAlgorithm | Algoritma | |
Contoh
Code Editor (JavaScript)
// A dictionary (e.g. results of ee.Image.reduceRegion of an S2 image).
var dict = ee.Dictionary({
B1: 182,
B2: 219,
B3: 443
});
/**
* Convert S2 surface reflectance units to native scale.
*/
function scale(key, value) {
return ee.Number(value).divide(1e4);
}
print('S2 surface reflectance in native units', dict.map(scale));
Penyiapan Python
Lihat halaman
Lingkungan Python untuk mengetahui informasi tentang Python API dan penggunaan
geemap untuk pengembangan interaktif.
import ee
import geemap.core as geemap
Colab (Python)
# A dictionary (e.g. results of ee.Image.reduceRegion of an S2 image).
dic = ee.Dictionary({
'B1': 182,
'B2': 219,
'B3': 443
})
def scale(key, value):
"""Convert S2 surface reflectance units to native scale."""
return ee.Number(value).divide(1e4)
print('S2 surface reflectance in native units:', dic.map(scale).getInfo())
Kecuali dinyatakan lain, konten di halaman ini dilisensikan berdasarkan Lisensi Creative Commons Attribution 4.0, sedangkan contoh kode dilisensikan berdasarkan Lisensi Apache 2.0. Untuk mengetahui informasi selengkapnya, lihat Kebijakan Situs Google Developers. Java adalah merek dagang terdaftar dari Oracle dan/atau afiliasinya.
Terakhir diperbarui pada 2025-07-26 UTC.
[null,null,["Terakhir diperbarui pada 2025-07-26 UTC."],[[["\u003cp\u003e\u003ccode\u003eDictionary.map()\u003c/code\u003e applies a provided algorithm to each key-value pair in a dictionary, transforming the values based on the algorithm's logic.\u003c/p\u003e\n"],["\u003cp\u003eThe algorithm used by \u003ccode\u003eDictionary.map()\u003c/code\u003e receives a key and its corresponding value as input, and it should return the new value for that key.\u003c/p\u003e\n"],["\u003cp\u003eIf the algorithm returns null for a specific key, that key-value pair will be excluded from the resulting dictionary.\u003c/p\u003e\n"],["\u003cp\u003e\u003ccode\u003eDictionary.map()\u003c/code\u003e is particularly useful for tasks like data transformation and filtering within dictionaries, offering a concise way to modify values based on custom logic.\u003c/p\u003e\n"],["\u003cp\u003eExample use cases include converting units of measurement within a dataset or selectively removing entries based on certain criteria applied to the key-value pairs.\u003c/p\u003e\n"]]],["The core content details the `map` function for dictionaries. This function applies a user-defined algorithm to each key-value pair within a dictionary. The algorithm takes a key and its corresponding value as input and returns a new value. The `map` function iterates through the dictionary, executes the provided algorithm on each pair, and generates a new dictionary with the updated values. If the algorithm's result is `null`, the key is removed from the resulting dictionary. Examples illustrate this with scaling values in a dictionary.\n"],null,["# ee.Dictionary.map\n\nMap an algorithm over a dictionary. The algorithm is expected to take 2 arguments, a key from the existing dictionary and the value it corresponds to, and return a new value for the given key. If the algorithm returns null, the key is dropped.\n\n\u003cbr /\u003e\n\n| Usage | Returns |\n|---------------------------------|------------|\n| Dictionary.map`(baseAlgorithm)` | Dictionary |\n\n| Argument | Type | Details |\n|--------------------|------------|---------|\n| this: `dictionary` | Dictionary | |\n| `baseAlgorithm` | Algorithm | |\n\nExamples\n--------\n\n### Code Editor (JavaScript)\n\n```javascript\n// A dictionary (e.g. results of ee.Image.reduceRegion of an S2 image).\nvar dict = ee.Dictionary({\n B1: 182,\n B2: 219,\n B3: 443\n});\n\n/**\n * Convert S2 surface reflectance units to native scale.\n */\nfunction scale(key, value) {\n return ee.Number(value).divide(1e4);\n}\n\nprint('S2 surface reflectance in native units', dict.map(scale));\n```\nPython setup\n\nSee the [Python Environment](/earth-engine/guides/python_install) page for information on the Python API and using\n`geemap` for interactive development. \n\n```python\nimport ee\nimport geemap.core as geemap\n```\n\n### Colab (Python)\n\n```python\n# A dictionary (e.g. results of ee.Image.reduceRegion of an S2 image).\ndic = ee.Dictionary({\n 'B1': 182,\n 'B2': 219,\n 'B3': 443\n})\n\n\ndef scale(key, value):\n \"\"\"Convert S2 surface reflectance units to native scale.\"\"\"\n return ee.Number(value).divide(1e4)\n\nprint('S2 surface reflectance in native units:', dic.map(scale).getInfo())\n```"]]
