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ee.ImageCollection.aggregate_first
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。
对集合中对象的指定属性进行聚合,计算集合中第一个对象的属性值。
用法 | 返回 |
---|
ImageCollection.aggregate_first(property) | |
参数 | 类型 | 详细信息 |
---|
此:collection | FeatureCollection | 要汇总的集合。 |
property | 字符串 | 要从集合的每个元素中使用的属性。 |
示例
代码编辑器 (JavaScript)
// A Lansat 8 TOA image collection for a specific year and location.
var col = ee.ImageCollection("LANDSAT/LC08/C02/T1_TOA")
.filterBounds(ee.Geometry.Point([-122.073, 37.188]))
.filterDate('2018', '2019');
// An image property of interest, percent cloud cover in this case.
var prop = 'CLOUD_COVER';
// Use ee.ImageCollection.aggregate_* functions to fetch information about
// values of a selected property across all images in the collection. For
// example, produce a list of all values, get counts, and calculate statistics.
print('List of property values', col.aggregate_array(prop));
print('Count of property values', col.aggregate_count(prop));
print('Count of distinct property values', col.aggregate_count_distinct(prop));
print('First collection element property value', col.aggregate_first(prop));
print('Histogram of property values', col.aggregate_histogram(prop));
print('Min of property values', col.aggregate_min(prop));
print('Max of property values', col.aggregate_max(prop));
// The following methods are applicable to numerical properties only.
print('Mean of property values', col.aggregate_mean(prop));
print('Sum of property values', col.aggregate_sum(prop));
print('Product of property values', col.aggregate_product(prop));
print('Std dev (sample) of property values', col.aggregate_sample_sd(prop));
print('Variance (sample) of property values', col.aggregate_sample_var(prop));
print('Std dev (total) of property values', col.aggregate_total_sd(prop));
print('Variance (total) of property values', col.aggregate_total_var(prop));
print('Summary stats of property values', col.aggregate_stats(prop));
// Note that if the property is formatted as a string, min and max will
// respectively return the first and last values according to alphanumeric
// order of the property values.
var propString = 'LANDSAT_SCENE_ID';
print('List of property values (string)', col.aggregate_array(propString));
print('Min of property values (string)', col.aggregate_min(propString));
print('Max of property values (string)', col.aggregate_max(propString));
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)
from pprint import pprint
# A Lansat 8 TOA image collection for a specific year and location.
col = ee.ImageCollection("LANDSAT/LC08/C02/T1_TOA").filterBounds(
ee.Geometry.Point([-122.073, 37.188])).filterDate('2018', '2019')
# An image property of interest, percent cloud cover in this case.
prop = 'CLOUD_COVER'
# Use ee.ImageCollection.aggregate_* functions to fetch information about
# values of a selected property across all images in the collection. For
# example, produce a list of all values, get counts, and calculate statistics.
print('List of property values:', col.aggregate_array(prop).getInfo())
print('Count of property values:', col.aggregate_count(prop).getInfo())
print('Count of distinct property values:',
col.aggregate_count_distinct(prop).getInfo())
print('First collection element property value:',
col.aggregate_first(prop).getInfo())
print('Histogram of property values:')
pprint(col.aggregate_histogram(prop).getInfo())
print('Min of property values:', col.aggregate_min(prop).getInfo())
print('Max of property values:', col.aggregate_max(prop).getInfo())
# The following methods are applicable to numerical properties only.
print('Mean of property values:', col.aggregate_mean(prop).getInfo())
print('Sum of property values:', col.aggregate_sum(prop).getInfo())
print('Product of property values:', col.aggregate_product(prop).getInfo())
print('Std dev (sample) of property values:',
col.aggregate_sample_sd(prop).getInfo())
print('Variance (sample) of property values:',
col.aggregate_sample_var(prop).getInfo())
print('Std dev (total) of property values:',
col.aggregate_total_sd(prop).getInfo())
print('Variance (total) of property values:',
col.aggregate_total_var(prop).getInfo())
print('Summary stats of property values')
pprint(col.aggregate_stats(prop).getInfo())
# Note that if the property is formatted as a string, min and max will
# respectively return the first and last values according to alphanumeric
# order of the property values.
prop_string = 'LANDSAT_SCENE_ID'
print('List of property values (string):',
col.aggregate_array(prop_string).getInfo())
print('Min of property values (string):',
col.aggregate_min(prop_string).getInfo())
print('Max of property values (string):',
col.aggregate_max(prop_string).getInfo())
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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\u003eaggregate_first\u003c/code\u003e calculates the value of a specified property from the first object within an ImageCollection.\u003c/p\u003e\n"],["\u003cp\u003eIt's useful for retrieving a representative property value from a collection.\u003c/p\u003e\n"],["\u003cp\u003eThe property can be any valid property associated with the objects in the collection.\u003c/p\u003e\n"],["\u003cp\u003eThe function returns the value of the specified property from the first element, or null if the collection is empty or the property is not found.\u003c/p\u003e\n"]]],["The content details the use of `aggregate_*` functions on an `ImageCollection`. These functions fetch information about a selected property across all images. Specific actions include retrieving a list of property values, counts, statistics, and histograms. `aggregate_first` retrieves the property value of the collection's first object. Other functions calculate minimum, maximum, mean, sum, product, standard deviation, and variance of numerical properties. String properties min and max values are ordered alphanumerically.\n"],null,["# ee.ImageCollection.aggregate_first\n\nAggregates over a given property of the objects in a collection, calculating the property value of the first object in the collection.\n\n\u003cbr /\u003e\n\n| Usage | Returns |\n|---------------------------------------------|---------|\n| ImageCollection.aggregate_first`(property)` | |\n\n| Argument | Type | Details |\n|--------------------|-------------------|----------------------------------------------------------|\n| this: `collection` | FeatureCollection | The collection to aggregate over. |\n| `property` | String | The property to use from each element of the collection. |\n\nExamples\n--------\n\n### Code Editor (JavaScript)\n\n```javascript\n// A Lansat 8 TOA image collection for a specific year and location.\nvar col = ee.ImageCollection(\"LANDSAT/LC08/C02/T1_TOA\")\n .filterBounds(ee.Geometry.Point([-122.073, 37.188]))\n .filterDate('2018', '2019');\n\n// An image property of interest, percent cloud cover in this case.\nvar prop = 'CLOUD_COVER';\n\n// Use ee.ImageCollection.aggregate_* functions to fetch information about\n// values of a selected property across all images in the collection. For\n// example, produce a list of all values, get counts, and calculate statistics.\nprint('List of property values', col.aggregate_array(prop));\nprint('Count of property values', col.aggregate_count(prop));\nprint('Count of distinct property values', col.aggregate_count_distinct(prop));\nprint('First collection element property value', col.aggregate_first(prop));\nprint('Histogram of property values', col.aggregate_histogram(prop));\nprint('Min of property values', col.aggregate_min(prop));\nprint('Max of property values', col.aggregate_max(prop));\n\n// The following methods are applicable to numerical properties only.\nprint('Mean of property values', col.aggregate_mean(prop));\nprint('Sum of property values', col.aggregate_sum(prop));\nprint('Product of property values', col.aggregate_product(prop));\nprint('Std dev (sample) of property values', col.aggregate_sample_sd(prop));\nprint('Variance (sample) of property values', col.aggregate_sample_var(prop));\nprint('Std dev (total) of property values', col.aggregate_total_sd(prop));\nprint('Variance (total) of property values', col.aggregate_total_var(prop));\nprint('Summary stats of property values', col.aggregate_stats(prop));\n\n// Note that if the property is formatted as a string, min and max will\n// respectively return the first and last values according to alphanumeric\n// order of the property values.\nvar propString = 'LANDSAT_SCENE_ID';\nprint('List of property values (string)', col.aggregate_array(propString));\nprint('Min of property values (string)', col.aggregate_min(propString));\nprint('Max of property values (string)', col.aggregate_max(propString));\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\nfrom pprint import pprint\n\n# A Lansat 8 TOA image collection for a specific year and location.\ncol = ee.ImageCollection(\"LANDSAT/LC08/C02/T1_TOA\").filterBounds(\n ee.Geometry.Point([-122.073, 37.188])).filterDate('2018', '2019')\n\n# An image property of interest, percent cloud cover in this case.\nprop = 'CLOUD_COVER'\n\n# Use ee.ImageCollection.aggregate_* functions to fetch information about\n# values of a selected property across all images in the collection. For\n# example, produce a list of all values, get counts, and calculate statistics.\nprint('List of property values:', col.aggregate_array(prop).getInfo())\nprint('Count of property values:', col.aggregate_count(prop).getInfo())\nprint('Count of distinct property values:',\n col.aggregate_count_distinct(prop).getInfo())\nprint('First collection element property value:',\n col.aggregate_first(prop).getInfo())\nprint('Histogram of property values:')\npprint(col.aggregate_histogram(prop).getInfo())\nprint('Min of property values:', col.aggregate_min(prop).getInfo())\nprint('Max of property values:', col.aggregate_max(prop).getInfo())\n\n# The following methods are applicable to numerical properties only.\nprint('Mean of property values:', col.aggregate_mean(prop).getInfo())\nprint('Sum of property values:', col.aggregate_sum(prop).getInfo())\nprint('Product of property values:', col.aggregate_product(prop).getInfo())\nprint('Std dev (sample) of property values:',\n col.aggregate_sample_sd(prop).getInfo())\nprint('Variance (sample) of property values:',\n col.aggregate_sample_var(prop).getInfo())\nprint('Std dev (total) of property values:',\n col.aggregate_total_sd(prop).getInfo())\nprint('Variance (total) of property values:',\n col.aggregate_total_var(prop).getInfo())\nprint('Summary stats of property values')\npprint(col.aggregate_stats(prop).getInfo())\n\n# Note that if the property is formatted as a string, min and max will\n# respectively return the first and last values according to alphanumeric\n# order of the property values.\nprop_string = 'LANDSAT_SCENE_ID'\nprint('List of property values (string):',\n col.aggregate_array(prop_string).getInfo())\nprint('Min of property values (string):',\n col.aggregate_min(prop_string).getInfo())\nprint('Max of property values (string):',\n col.aggregate_max(prop_string).getInfo())\n```"]]