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ee.Algorithms.If
使用集合让一切井井有条
根据您的偏好保存内容并对其进行分类。
根据条件选择其中一个输入，类似于 if-then-else 结构。
| 用法 | 返回 |
|---|
ee.Algorithms.If(condition, trueCase, falseCase) | 对象 |
| 参数 | 类型 | 详细信息 |
|---|
condition | 对象，默认值：null | 用于确定返回哪个结果的条件。如果此值不是布尔值，则会根据以下规则将其解读为布尔值：
- 等于 0 或 NaN 的数字为 false。
- 空字符串、列表和字典为 false。
- Null 为 false。
- 其他一切都是正确的。
|
trueCase | 对象，默认值：null | 如果条件为 true，则返回相应结果。 |
falseCase | 对象，默认值：null | 如果条件为 false，则返回相应结果。 |
示例
代码编辑器 (JavaScript)
print(ee.Algorithms.If(false, '*true*', '*false*')); // The string "*false*"
print(ee.Algorithms.If(true, '*true*', '*false*')); // The string "*true*"
// Consider using remap rather than If for tasks like numbers for classes.
print(ee.Algorithms.If(ee.String('Tree').compareTo('Tree'), 0, 1));
print(ee.Algorithms.If(ee.String('NotTree').compareTo('Tree'), 0, 1));
Python 设置
如需了解 Python API 和如何使用 geemap 进行交互式开发，请参阅
Python 环境页面。
import ee
import geemap.core as geemap
Colab (Python)
# The string "*false*"
print(ee.Algorithms.If(False, '*true*', '*false*').getInfo())
# The string "*true*"
print(ee.Algorithms.If(True, '*true*', '*false*').getInfo())
# Consider using remap rather than If for tasks like numbers for classes.
print(ee.Algorithms.If(ee.String('Tree').compareTo('Tree'), 0, 1).getInfo())
print(ee.Algorithms.If(ee.String('NotTree').compareTo('Tree'), 0, 1).getInfo())
如未另行说明，那么本页面中的内容已根据知识共享署名 4.0 许可获得了许可，并且代码示例已根据 Apache 2.0 许可获得了许可。有关详情，请参阅 Google 开发者网站政策。Java 是 Oracle 和/或其关联公司的注册商标。
最后更新时间 (UTC)：2025-07-26。
[null,null,["最后更新时间 (UTC)：2025-07-26。"],[[["\u003cp\u003e\u003ccode\u003eee.Algorithms.If\u003c/code\u003e selects one of two input values based on a given condition, similar to an if-then-else statement.\u003c/p\u003e\n"],["\u003cp\u003eThe \u003ccode\u003econdition\u003c/code\u003e input determines the output, treating non-boolean values as true or false based on specific rules (e.g., 0 is false, empty strings are false).\u003c/p\u003e\n"],["\u003cp\u003e\u003ccode\u003etrueCase\u003c/code\u003e and \u003ccode\u003efalseCase\u003c/code\u003e represent the values returned when the condition is true or false, respectively.\u003c/p\u003e\n"],["\u003cp\u003eWhile \u003ccode\u003eee.Algorithms.If\u003c/code\u003e is versatile, using \u003ccode\u003eremap\u003c/code\u003e might be more efficient for tasks like assigning numerical values to classes.\u003c/p\u003e\n"]]],["The `ee.Algorithms.If` function selects one of two inputs based on a condition. It takes a `condition`, `trueCase`, and `falseCase`. If the `condition` is true, it returns `trueCase`; otherwise, it returns `falseCase`. Non-boolean conditions are evaluated: 0, NaN, empty collections, and null are false; everything else is true. Examples show using boolean values and string comparisons as conditions to determine the returned value. The `remap` function is suggested as an alternative for class-numbering tasks.\n"],null,["# ee.Algorithms.If\n\nSelects one of its inputs based on a condition, similar to an if-then-else construct.\n\n\u003cbr /\u003e\n\n| Usage | Returns |\n|------------------------------------------------------------------|---------|\n| `ee.Algorithms.If(`*condition* `, `*trueCase* `, `*falseCase*`)` | Object |\n\n| Argument | Type | Details |\n|-------------|-----------------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|\n| `condition` | Object, default: null | The condition that determines which result is returned. If this is not a boolean, it is interpreted as a boolean by the following rules: - Numbers that are equal to 0 or a NaN are false. - Empty strings, lists and dictionaries are false. - Null is false. - Everything else is true. |\n| `trueCase` | Object, default: null | The result to return if the condition is true. |\n| `falseCase` | Object, default: null | The result to return if the condition is false. |\n\nExamples\n--------\n\n### Code Editor (JavaScript)\n\n```javascript\nprint(ee.Algorithms.If(false, '*true*', '*false*')); // The string \"*false*\"\nprint(ee.Algorithms.If(true, '*true*', '*false*')); // The string \"*true*\"\n\n// Consider using remap rather than If for tasks like numbers for classes.\nprint(ee.Algorithms.If(ee.String('Tree').compareTo('Tree'), 0, 1));\nprint(ee.Algorithms.If(ee.String('NotTree').compareTo('Tree'), 0, 1));\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# The string \"*false*\"\nprint(ee.Algorithms.If(False, '*true*', '*false*').getInfo())\n\n# The string \"*true*\"\nprint(ee.Algorithms.If(True, '*true*', '*false*').getInfo())\n\n# Consider using remap rather than If for tasks like numbers for classes.\nprint(ee.Algorithms.If(ee.String('Tree').compareTo('Tree'), 0, 1).getInfo())\nprint(ee.Algorithms.If(ee.String('NotTree').compareTo('Tree'), 0, 1).getInfo())\n```"]]
