Array Overview

  • The ee.Array type in Earth Engine is used to represent multi-dimensional data structures like vectors, matrices, and cubes.

  • Arrays offer flexibility and power but may not scale as efficiently as other Earth Engine data structures for problems solvable without them.

  • Use the ee.Array class when problems require higher dimension modeling, flexible linear algebra, or other functionalities unique to arrays.

  • An array's dimension is the number of axes, its shape is determined by axis lengths, and its size is the product of axis lengths, with all elements having the same type and no sparse or ragged arrays supported.

Earth Engine represents 1-D vectors, 2-D matrices, 3-D cubes, and higher dimensional hypercubes with the ee.Array type. Arrays are a flexible data structure, but in exchange for the power they offer, they do not scale as well as other data structures in Earth Engine. If the problem can be solved without using arrays, the result will be computed faster and more efficiently. But if the problem requires a higher dimension model, flexible linear algebra, or anything else arrays are uniquely suited to, you can use the Array class.

Array dimension, shape and size

The dimension of an array refers to the number of axes along which the underlying data varies. For example, 0-D arrays are scalar numbers, 1-D arrays are vectors, 2-D arrays are matrices, 3-D arrays are cubes, and >3-D arrays are hyper-cubes. For an N-dimensional array, there are N axes from 0 to N-1. The shape of the array is determined by the lengths of the axes. The length of an axis is the number of positions along it. The array size, or number of total elements in the array, equals the product of the axis lengths. Each value at every position on every axis must have a valid number, since sparse or ragged arrays are not currently supported. The array’s element type indicates what kind of number each element is; all elements of the array will have the same type.