ee.Number.expression
Computes a numeric expression.
Usage | Returns | ee.Number.expression(expression, vars) | Number |
Argument | Type | Details | expression | String | A mathematical expression string to be evaluated. In addition to the standard arithmetic, boolean and relational operators, expressions also support any function in Number, the '.' operator to extract child elements from the 'vars' dictionary, and mathematical constants Math.PI and Math.E. |
vars | Dictionary, default: null | A dictionary of named values that can be used in the expression. |
Examples
Code Editor (JavaScript)
// A dictionary of variables to use in expression.
var variables = {x: 5, y: 10};
// Arithmetic operators.
print('x + y',
ee.Number.expression('x + y', variables));
print('x - y',
ee.Number.expression('x - y', variables));
print('x * y',
ee.Number.expression('x * y', variables));
print('x / y',
ee.Number.expression('x / y', variables));
print('x ** y',
ee.Number.expression('x ** y', variables));
print('x % y',
ee.Number.expression('x % y', variables));
// Logical operators.
print('x || y',
ee.Number.expression('x || y', variables));
print('x && y',
ee.Number.expression('x && y', variables));
print('!(x)',
ee.Number.expression('!(x)', variables));
// Relational operators.
print('x > y',
ee.Number.expression('x > y', variables));
print('x >= y',
ee.Number.expression('x >= y', variables));
print('x < y',
ee.Number.expression('x < y', variables));
print('x <= y',
ee.Number.expression('x <= y', variables));
print('x == y',
ee.Number.expression('x == y', variables));
print('x != y',
ee.Number.expression('x != y', variables));
// Conditional (ternary) operator.
print('(x < y) ? 100 : 1000)',
ee.Number.expression('(x < y) ? 100 : 1000', variables));
// Constants in the expression.
print('100 * (x + y)',
ee.Number.expression('100 * (x + y)', variables));
// JavaScript Math constants.
print('Math.PI',
ee.Number.expression('Math.PI', null));
print('Math.E',
ee.Number.expression('Math.E', null));
// Dot notation to call on child elements.
print('Use dot notation to call on child elements',
ee.Number.expression('vals.x * vals.y', {vals: variables}));
// ee.Number functions.
print('Use ee.Number add: add(x, y)',
ee.Number.expression('add(x, y)', variables));
print('Use ee.Number add and subtract: subtract(add(x, y), 5)',
ee.Number.expression('subtract(add(x, y), 5)', variables));
Python setup
See the
Python Environment page for information on the Python API and using
geemap
for interactive development.
import ee
import geemap.core as geemap
Colab (Python)
# A dictionary of variables to use in expression.
variables = {'x': 5, 'y': 10}
# Arithmetic operators.
print('x + y:',
ee.Number.expression('x + y', variables).getInfo())
print('x - y:',
ee.Number.expression('x - y', variables).getInfo())
print('x * y:',
ee.Number.expression('x * y', variables).getInfo())
print('x / y:',
ee.Number.expression('x / y', variables).getInfo())
print('x ** y:',
ee.Number.expression('x ** y', variables).getInfo())
print('x % y:',
ee.Number.expression('x % y', variables).getInfo())
# Logical operators.
print('x || y:',
ee.Number.expression('x || y', variables).getInfo())
print('x && y:',
ee.Number.expression('x && y', variables).getInfo())
print('!(x):',
ee.Number.expression('!(x)', variables).getInfo())
# Relational operators.
print('x > y:',
ee.Number.expression('x > y', variables).getInfo())
print('x >= y:',
ee.Number.expression('x >= y', variables).getInfo())
print('x < y:',
ee.Number.expression('x < y', variables).getInfo())
print('x <= y:',
ee.Number.expression('x <= y', variables).getInfo())
print('x == y:',
ee.Number.expression('x == y', variables).getInfo())
print('x != y:',
ee.Number.expression('x != y', variables).getInfo())
# Conditional JavaScript (ternary) operator.
print('(x < y) ? 100 : 1000):',
ee.Number.expression('(x < y) ? 100 : 1000', variables).getInfo())
# Constants in the expression.
print('100 * (x + y):',
ee.Number.expression('100 * (x + y)', variables).getInfo())
# JavaScript Math constants.
print('Math.PI:',
ee.Number.expression('Math.PI', None).getInfo())
print('Math.E:',
ee.Number.expression('Math.E', None).getInfo())
# Dot notation to call on child elements.
print('Use dot notation to call on child elements:',
ee.Number.expression('vals.x * vals.y', {'vals': variables}).getInfo())
# ee.Number functions.
print('Use ee.Number add. add(x, y):',
ee.Number.expression('add(x, y)', variables).getInfo())
print('Use ee.Number add and subtract. subtract(add(x, y), 5):',
ee.Number.expression('subtract(add(x, y), 5)', variables).getInfo())
Except as otherwise noted, the content of this page is licensed under the Creative Commons Attribution 4.0 License, and code samples are licensed under the Apache 2.0 License. For details, see the Google Developers Site Policies. Java is a registered trademark of Oracle and/or its affiliates.
Last updated 2024-07-13 UTC.
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