公告:所有在
2025 年 4 月 15 日之前注册使用 Earth Engine 的非商业项目都必须
验证是否符合非商业性质的资格条件,才能继续使用 Earth Engine。
ee.Image.arrayLength
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。
返回每个像素数组沿指定轴的长度。
用法 | 返回 |
---|
Image.arrayLength(axis) | 图片 |
参数 | 类型 | 详细信息 |
---|
此:input | 图片 | 输入图片。 |
axis | 整数 | 要获取长度的轴。 |
示例
代码编辑器 (JavaScript)
// A function to print arrays for a selected pixel in the following examples.
function sampArrImg(arrImg) {
var point = ee.Geometry.Point([-121, 42]);
return arrImg.sample(point, 500).first().get('array');
}
// A 3-band image of constants.
var img = ee.Image([0, 1, 2]);
print('3-band image', img);
// Convert the 3-band image to a 2D array image.
var arrayImg2D = img.toArray().toArray(1);
print('2D array image (pixel)', sampArrImg(arrayImg2D));
// [[0],
// [1],
// [2]]
// Get the number of dimensions in each pixel's array.
var arrayImg2Ddim = arrayImg2D.arrayDimensions();
print('N dimensions in array', sampArrImg(arrayImg2Ddim));
// 2
// Get the array length per dimension per pixel.
var arrayImg2DdimLen = arrayImg2D.arrayLengths();
print('Array length per dimension', sampArrImg(arrayImg2DdimLen));
// [3, 1]
// Get the array length for 0-axis (rows).
var arrayImg2Daxis0Len = arrayImg2D.arrayLength(0);
print('Array length 0-axis (rows)', sampArrImg(arrayImg2Daxis0Len));
// 3
// Get the array length for 1-axis (columns).
var arrayImg2Daxis1Len = arrayImg2D.arrayLength(1);
print('Array length 1-axis (columns)', sampArrImg(arrayImg2Daxis1Len));
// 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)
# A function to print arrays for a selected pixel in the following examples.
def samp_arr_img(arr_img):
point = ee.Geometry.Point([-121, 42])
return arr_img.sample(point, 500).first().get('array')
# A 3-band image of constants.
img = ee.Image([0, 1, 2])
print('3-band image:', img.getInfo())
# Convert the 3-band image to a 2D array image.
array_img_2d = img.toArray().toArray(1)
print('2D array image (pixel):', samp_arr_img(array_img_2d).getInfo())
# [[0],
# [1],
# [2]]
# Get the number of dimensions in each pixel's array.
array_img2d_dim = array_img_2d.arrayDimensions()
print('N dimensions in array:', samp_arr_img(array_img2d_dim).getInfo())
# 2
# Get the array length per dimension per pixel.
array_img_2d_dim_len = array_img_2d.arrayLengths()
print(
'Array length per dimension:',
samp_arr_img(array_img_2d_dim_len).getInfo()
)
# [3, 1]
# Get the array length for 0-axis (rows).
array_img2d_axis0_len = array_img_2d.arrayLength(0)
print(
'Array length 0-axis (rows):',
samp_arr_img(array_img2d_axis0_len).getInfo()
)
# 3
# Get the array length for 1-axis (columns).
array_img_2d_axis1_len = array_img_2d.arrayLength(1)
print(
'Array length 1-axis (columns):',
samp_arr_img(array_img_2d_axis1_len).getInfo()
)
# 1
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\u003earrayLength()\u003c/code\u003e returns the length of each pixel's array along a specified axis in an image.\u003c/p\u003e\n"],["\u003cp\u003eIt's used to get the size of array dimensions within images that have been converted to array format.\u003c/p\u003e\n"],["\u003cp\u003eThis function is crucial for understanding the structure and dimensions of array-based images in Earth Engine.\u003c/p\u003e\n"],["\u003cp\u003eBy providing the axis as an argument, you can get the length for specific dimensions (like rows or columns) of the array.\u003c/p\u003e\n"]]],[],null,["# ee.Image.arrayLength\n\nReturns the length of each pixel's array along the given axis.\n\n\u003cbr /\u003e\n\n| Usage | Returns |\n|---------------------------|---------|\n| Image.arrayLength`(axis)` | Image |\n\n| Argument | Type | Details |\n|---------------|---------|------------------------------------------|\n| this: `input` | Image | Input image. |\n| `axis` | Integer | The axis along which to take the length. |\n\nExamples\n--------\n\n### Code Editor (JavaScript)\n\n```javascript\n// A function to print arrays for a selected pixel in the following examples.\nfunction sampArrImg(arrImg) {\n var point = ee.Geometry.Point([-121, 42]);\n return arrImg.sample(point, 500).first().get('array');\n}\n\n// A 3-band image of constants.\nvar img = ee.Image([0, 1, 2]);\nprint('3-band image', img);\n\n// Convert the 3-band image to a 2D array image.\nvar arrayImg2D = img.toArray().toArray(1);\nprint('2D array image (pixel)', sampArrImg(arrayImg2D));\n// [[0],\n// [1],\n// [2]]\n\n// Get the number of dimensions in each pixel's array.\nvar arrayImg2Ddim = arrayImg2D.arrayDimensions();\nprint('N dimensions in array', sampArrImg(arrayImg2Ddim));\n// 2\n\n// Get the array length per dimension per pixel.\nvar arrayImg2DdimLen = arrayImg2D.arrayLengths();\nprint('Array length per dimension', sampArrImg(arrayImg2DdimLen));\n// [3, 1]\n\n// Get the array length for 0-axis (rows).\nvar arrayImg2Daxis0Len = arrayImg2D.arrayLength(0);\nprint('Array length 0-axis (rows)', sampArrImg(arrayImg2Daxis0Len));\n// 3\n\n// Get the array length for 1-axis (columns).\nvar arrayImg2Daxis1Len = arrayImg2D.arrayLength(1);\nprint('Array length 1-axis (columns)', sampArrImg(arrayImg2Daxis1Len));\n// 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# A function to print arrays for a selected pixel in the following examples.\ndef samp_arr_img(arr_img):\n point = ee.Geometry.Point([-121, 42])\n return arr_img.sample(point, 500).first().get('array')\n\n# A 3-band image of constants.\nimg = ee.Image([0, 1, 2])\nprint('3-band image:', img.getInfo())\n\n# Convert the 3-band image to a 2D array image.\narray_img_2d = img.toArray().toArray(1)\nprint('2D array image (pixel):', samp_arr_img(array_img_2d).getInfo())\n# [[0],\n# [1],\n# [2]]\n\n# Get the number of dimensions in each pixel's array.\narray_img2d_dim = array_img_2d.arrayDimensions()\nprint('N dimensions in array:', samp_arr_img(array_img2d_dim).getInfo())\n# 2\n\n# Get the array length per dimension per pixel.\narray_img_2d_dim_len = array_img_2d.arrayLengths()\nprint(\n 'Array length per dimension:',\n samp_arr_img(array_img_2d_dim_len).getInfo()\n)\n# [3, 1]\n\n# Get the array length for 0-axis (rows).\narray_img2d_axis0_len = array_img_2d.arrayLength(0)\nprint(\n 'Array length 0-axis (rows):',\n samp_arr_img(array_img2d_axis0_len).getInfo()\n)\n# 3\n\n# Get the array length for 1-axis (columns).\narray_img_2d_axis1_len = array_img_2d.arrayLength(1)\nprint(\n 'Array length 1-axis (columns):',\n samp_arr_img(array_img_2d_axis1_len).getInfo()\n)\n# 1\n```"]]