ee.ImageCollection.fromImages

Trả về bộ sưu tập hình ảnh chứa các hình ảnh đã cho.

Cách sử dụng	Giá trị trả về
ee.ImageCollection.fromImages(images)	ImageCollection

Đối số	Loại	Thông tin chi tiết
images	Danh sách	Hình ảnh cần đưa vào bộ sưu tập.

Ví dụ

Trình soạn thảo mã (JavaScript)

// A series of images.
var img1 = ee.Image(0);
var img2 = ee.Image(1);
var img3 = ee.Image(2);

// Convert the list of images into an image collection.
var col = ee.ImageCollection.fromImages([img1, img2, img3]);
print('Collection from list of images', col);

// The ee.ImageCollection.fromImages function is intended to coerce the image
// list to a collection when the list is an ambiguous, computed object fetched
// from the properties of a server-side object. For instance, a list
// of images retrieved from a ee.Feature property. Here, we set an image
// list as a property of a feature, retrieve it, and convert it to
// a collection. Notice that the ee.ImageCollection constructor fails to coerce
// the image list to a collection, but ee.ImageCollection.fromImages does.
var feature = ee.Feature(null).set('img_list', [img1, img2, img3]);
var ambiguousImgList = feature.get('img_list');
print('Coerced to collection', ee.ImageCollection.fromImages(ambiguousImgList));
print('NOT coerced to collection', ee.ImageCollection(ambiguousImgList));

// A common use case is coercing an image list from a saveAll join to a
// image collection, like in this example of building a collection of mean
// annual NDVI images from a MODIS collection.
var modisCol = ee.ImageCollection('MODIS/061/MOD13A2')
  .filterDate('2017', '2021')
  .select('NDVI')
  .map(function(img) {return img.set('year', img.date().get('year'))});

var distinctYearCol = modisCol.distinct('year');

var joinedCol = ee.Join.saveAll('img_list').apply({
  primary: distinctYearCol,
  secondary: modisCol,
  condition: ee.Filter.equals({'leftField': 'year', 'rightField': 'year'})
});

var annualNdviMean = joinedCol.map(function(img) {
  return ee.ImageCollection.fromImages(img.get('img_list')).mean()
    .copyProperties(img, ['year']);
});
print('Mean annual NDVI collection', annualNdviMean);

Thiết lập Python

Hãy xem trang Môi trường Python để biết thông tin về API Python và cách sử dụng geemap cho quá trình phát triển tương tác.

import ee
import geemap.core as geemap

Colab (Python)

# A series of images.
img1 = ee.Image(0)
img2 = ee.Image(1)
img3 = ee.Image(2)

# Convert the list of images into an image collection.
col = ee.ImageCollection.fromImages([img1, img2, img3])
display('Collection from list of images:', col)

# The ee.ImageCollection.fromImages function is intended to coerce the image
# list to a collection when the list is an ambiguous, computed object fetched
# from the properties of a server-side object. For instance, a list
# of images retrieved from a ee.Feature property. Here, we set an image
# list as a property of a feature, retrieve it, and convert it to
# a collection. Notice that the ee.ImageCollection constructor fails to coerce
# the image list to a collection, but ee.ImageCollection.fromImages does.
feature = ee.Feature(None).set('img_list', [img1, img2, img3])
ambiguous_img_list = feature.get('img_list')
display(
    'Coerced to collection:',
    ee.ImageCollection.fromImages(ambiguous_img_list),
)
display(
    'NOT coerced to collection:',
    ee.ImageCollection(ambiguous_img_list),
)

# A common use case is coercing an image list from a saveAll join to a
# image collection, like in this example of building a collection of mean
# annual NDVI images from a MODIS collection.
modis_col = (
    ee.ImageCollection('MODIS/061/MOD13A2')
    .filterDate('2017', '2021')
    .select('NDVI')
    .map(lambda img: img.set('year', img.date().get('year')))
)

distinct_year_col = modis_col.distinct('year')

joined_col = ee.Join.saveAll('img_list').apply(
    primary=distinct_year_col,
    secondary=modis_col,
    condition=ee.Filter.equals(leftField='year', rightField='year'),
)

annual_ndvi_mean = joined_col.map(
    lambda img: ee.ImageCollection.fromImages(img.get('img_list'))
    .mean()
    .copyProperties(img, ['year'])
)
display('Mean annual NDVI collection:', annual_ndvi_mean)