ee.Number.expression

Berechnet einen numerischen Ausdruck.

Nutzung	Ausgabe
ee.Number.expression(expression, vars)	Zahl

Argument	Typ	Details
expression	String	Ein String mit einem mathematischen Ausdruck, der ausgewertet werden soll. Zusätzlich zu den standardmäßigen arithmetischen, booleschen und relationalen Operatoren unterstützen Ausdrücke auch alle Funktionen in Number, den Operator „.“ zum Extrahieren untergeordneter Elemente aus dem „vars“-Dictionary sowie die mathematischen Konstanten Math.PI und Math.E.
vars	Wörterbuch, Standardwert: null	Ein Dictionary mit benannten Werten, die im Ausdruck verwendet werden können.

Beispiele

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 einrichten

Informationen zur Python API und zur Verwendung von geemap für die interaktive Entwicklung finden Sie auf der Seite Python-Umgebung.

import ee
import geemap.core as geemap

Colab (Python)

# A dictionary of variables to use in expression.
variables = {'x': 5, 'y': 10}

# Arithmetic operators.
display('x + y:',
        ee.Number.expression('x + y', variables))
display('x - y:',
        ee.Number.expression('x - y', variables))
display('x * y:',
        ee.Number.expression('x * y', variables))
display('x / y:',
        ee.Number.expression('x / y', variables))
display('x ** y:',
        ee.Number.expression('x ** y', variables))
display('x % y:',
        ee.Number.expression('x % y', variables))

# Logical operators.
display('x || y:',
        ee.Number.expression('x || y', variables))
display('x && y:',
        ee.Number.expression('x && y', variables))
display('!(x):',
        ee.Number.expression('!(x)', variables))

# Relational operators.
display('x > y:',
        ee.Number.expression('x > y', variables))
display('x >= y:',
        ee.Number.expression('x >= y', variables))
display('x < y:',
        ee.Number.expression('x < y', variables))
display('x <= y:',
        ee.Number.expression('x <= y', variables))
display('x == y:',
        ee.Number.expression('x == y', variables))
display('x != y:',
        ee.Number.expression('x != y', variables))

# Conditional JavaScript (ternary) operator.
display('(x < y) ? 100 : 1000):',
        ee.Number.expression('(x < y) ? 100 : 1000', variables))

# Constants in the expression.
display('100 * (x + y):',
        ee.Number.expression('100 * (x + y)', variables))

# JavaScript Math constants.
display('Math.PI:',
        ee.Number.expression('Math.PI', None))
display('Math.E:',
        ee.Number.expression('Math.E', None))

# Dot notation to call on child elements.
display('Use dot notation to call on child elements:',
        ee.Number.expression('vals.x * vals.y', {'vals': variables}))

# ee.Number functions.
display('Use ee.Number add. add(x, y):',
        ee.Number.expression('add(x, y)', variables))
display('Use ee.Number add and subtract. subtract(add(x, y), 5):',
        ee.Number.expression('subtract(add(x, y), 5)', variables))