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ee.List.iterate
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。
对列表中的元素运行算法。该算法应接受两个对象:当前列表项和上一次迭代的结果(或第一次迭代的“first”值)。
用法 | 返回 |
---|
List.iterate(function, first) | 对象 |
参数 | 类型 | 详细信息 |
---|
此:list | 列表 | |
function | 算法 | |
first | 对象 | |
示例
代码编辑器 (JavaScript)
// This example uses the ee.List.iterate function to generate a series of
// sequentially halved values.
// Declare a list that will hold the series of sequentially halved values,
// initialize it with the starting quantity.
var quantityList = [1000];
// Define the number of iterations as a list sequence.
var nSteps = ee.List.sequence(1, 10);
// Declare a function that takes the current element of the iteration list and
// the returned result of the previous iteration as inputs. In this case, the
// the function is returning an accumulating list of quantities that are reduced
// by half at each iteration.
var halfOfPrevious = function(currentElement, previousResult) {
var previousQuantity = ee.Number(ee.List(previousResult).get(-1));
var currentQuantity = previousQuantity.divide(2);
return ee.List(previousResult).add(currentQuantity);
};
// Apply the function to the nSteps list, each element is an iteration.
quantityList = ee.List(nSteps.iterate(halfOfPrevious, quantityList));
// Display the results. Note that step 0 is included for the initial value.
print('Steps in the iteration of halved quantities', nSteps);
print('Series of sequentially halved quantities', quantityList);
print(ui.Chart.array.values({
array: quantityList,
axis: 0,
xLabels: ee.List([0]).cat(nSteps)
}));
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)
import matplotlib.pyplot as plt
# This example uses the ee.List.iterate function to generate a series of
# sequentially halved values.
# Declare a list that will hold the series of sequentially halved values,
# initialize it with the starting quantity.
quantity_list = [1000]
# Define the number of iterations as a list sequence.
n_steps = ee.List.sequence(1, 10)
# Declare a function that takes the current element of the iteration list and
# the returned result of the previous iteration as inputs. In this case, the
# the function is returning an accumulating list of quantities that are reduced
# by half at each iteration.
def half_of_previous(current_element, previous_result):
previous_quantity = ee.Number(ee.List(previous_result).get(-1))
current_quantity = previous_quantity.divide(2)
return ee.List(previous_result).add(current_quantity)
# Apply the function to the n_steps list, each element is an iteration.
quantity_list = ee.List(n_steps.iterate(half_of_previous, quantity_list))
# Display the results.
display('Steps in the iteration of halved quantities', n_steps)
display('Series of sequentially halved quantities', quantity_list)
quantity_list_client = quantity_list.getInfo()
plt.scatter(range(len(quantity_list_client)), quantity_list_client)
plt.show()
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最后更新时间 (UTC):2025-07-26。
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