Stay organized with collectionsSave and categorize content based on your preferences.
Accumulates elements of each array pixel along the given axis, by setting each element of the result array pixel to the reduction of elements in that pixel along the given axis, up to and including the current position on the axis. May be used to make a cumulative sum, a monotonically increasing sequence, etc.
Usage
Returns
Image.arrayAccum(axis,reducer)
Image
Argument
Type
Details
this:input
Image
Input image.
axis
Integer
Axis along which to perform the cumulative sum.
reducer
Reducer, default: null
Reducer to accumulate values. Default is SUM, to produce the cumulative sum of each vector along the given axis.
[[["Easy to understand","easyToUnderstand","thumb-up"],["Solved my problem","solvedMyProblem","thumb-up"],["Other","otherUp","thumb-up"]],[["Missing the information I need","missingTheInformationINeed","thumb-down"],["Too complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2023-10-06 UTC."],[[["\u003cp\u003e\u003ccode\u003eImage.arrayAccum()\u003c/code\u003e calculates the cumulative reduction of elements within each pixel of an array image along a specified axis.\u003c/p\u003e\n"],["\u003cp\u003eIt uses a reducer (defaulting to sum) to determine how elements are accumulated, producing a new array image.\u003c/p\u003e\n"],["\u003cp\u003eThe axis argument specifies the direction of accumulation (0 for rows, 1 for columns in 2D arrays).\u003c/p\u003e\n"],["\u003cp\u003eThis function is useful for generating cumulative sums, monotonically increasing sequences, and other cumulative calculations within array images.\u003c/p\u003e\n"],["\u003cp\u003eIt's applicable to both 1D and multidimensional array images in Earth Engine.\u003c/p\u003e\n"]]],[],null,["# ee.Image.arrayAccum\n\nAccumulates elements of each array pixel along the given axis, by setting each element of the result array pixel to the reduction of elements in that pixel along the given axis, up to and including the current position on the axis. May be used to make a cumulative sum, a monotonically increasing sequence, etc.\n\n\u003cbr /\u003e\n\n| Usage | Returns |\n|---------------------------------------|---------|\n| Image.arrayAccum`(axis, `*reducer*`)` | Image |\n\n| Argument | Type | Details |\n|---------------|------------------------|------------------------------------------------------------------------------------------------------------------|\n| this: `input` | Image | Input image. |\n| `axis` | Integer | Axis along which to perform the cumulative sum. |\n| `reducer` | Reducer, default: null | Reducer to accumulate values. Default is SUM, to produce the cumulative sum of each vector along the given axis. |\n\nExamples\n--------\n\n### Code Editor (JavaScript)\n\n```javascript\n// A function to print the array 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// Create a 1D array image.\nvar arrayImg1D = ee.Image([1, 2, 3]).toArray();\nprint('1D array image (pixel)', sampArrImg(arrayImg1D));\n// [1, 2, 3]\n\n// Perform accumulation procedures along axes using ee.Reducer functions.\n// Here we calculate the cumulative sum along the 0-axis for a 1D array.\nvar accumSum1DAx0 = arrayImg1D.arrayAccum(0, ee.Reducer.sum());\nprint('Cumulative sum along 0-axis', sampArrImg(accumSum1DAx0));\n// [1, 3, 6]\n\n// Create a 2D 3x3 array image.\nvar arrayImg2D = ee.Image([1, 2, 3, 4, 5, 6, 7, 8, 9]).toArray()\n .arrayReshape(ee.Image([3, 3]).toArray(), 2);\nprint('2D 3x3 array image (pixel)', sampArrImg(arrayImg2D));\n// [[1, 2, 3],\n// [4, 5, 6],\n// [7, 8, 9]]\n\n// Calculate the cumulative sum along the 0-axis for a 2D array.\nvar accumSum2DAx0 = arrayImg2D.arrayAccum(0, ee.Reducer.sum());\nprint('Cumulative sum along 0-axis', sampArrImg(accumSum2DAx0));\n// [[ 1, 2, 3],\n// [ 5, 7, 9],\n// [12, 15, 18]]\n\n// Calculate the cumulative sum along the 1-axis for a 2D array.\nvar accumSum2DAx1 = arrayImg2D.arrayAccum(1, ee.Reducer.sum());\nprint('Cumulative sum along 1-axis', sampArrImg(accumSum2DAx1));\n// [[1, 3, 6],\n// [4, 9, 15],\n// [7, 15, 24]]\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 the array 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# Create a 1D array image.\narray_img_1d = ee.Image([1, 2, 3]).toArray()\nprint('1D array image (pixel):', samp_arr_img(array_img_1d).getInfo())\n# [1, 2, 3]\n\n# Perform accumulation procedures along axes using ee.Reducer functions.\n# Here we calculate the cumulative sum along the 0-axis for a 1D array.\naccum_sum_1d_ax0 = array_img_1d.arrayAccum(0, ee.Reducer.sum())\nprint('Cumulative sum along 0-axis:', samp_arr_img(accum_sum_1d_ax0).getInfo())\n# [1, 3, 6]\n\n# Create a 2D 3x3 array image.\narray_img_2d = ee.Image([1, 2, 3, 4, 5, 6, 7, 8, 9]).toArray().arrayReshape(\n ee.Image([3, 3]).toArray(),\n 2)\nprint('2D 3x3 array image (pixel):', samp_arr_img(array_img_2d).getInfo())\n# [[1, 2, 3],\n# [4, 5, 6],\n# [7, 8, 9]]\n\n# Calculate the cumulative sum along the 0-axis for a 2D array.\naccum_sum_2d_ax0 = array_img_2d.arrayAccum(0, ee.Reducer.sum())\nprint('Cumulative sum along 0-axis:', samp_arr_img(accum_sum_2d_ax0).getInfo())\n# [[ 1, 2, 3],\n# [ 5, 7, 9],\n# [12, 15, 18]]\n\n# Calculate the cumulative sum along the 1-axis for a 2D array.\naccum_sum_2d_ax1 = array_img_2d.arrayAccum(1, ee.Reducer.sum())\nprint('Cumulative sum along 1-axis:', samp_arr_img(accum_sum_2d_ax1).getInfo())\n# [[1, 3, 6],\n# [4, 9, 15],\n# [7, 15, 24]]\n```"]]
