AI-generated Key Takeaways
-
Date.evaluate()
retrieves the value of a server-sideee.Date
object and passes it to a callback function. -
The callback function receives the evaluated result as an object with
type
andvalue
keys, wherevalue
represents milliseconds since the Unix epoch. -
Excessive use of
evaluate
can impact performance due to data transfer from Earth Engine servers to the client. -
The Python client library uses
getInfo()
instead ofevaluate
for asynchronous evaluation ofee.Date
objects.
Usage | Returns |
---|---|
Date.evaluate(callback) |
Argument | Type | Details |
---|---|---|
this: computedobject | ComputedObject | The ComputedObject instance. |
callback | Function | A function of the form function(success, failure), called when the server returns an answer. If the request succeeded, the success argument contains the evaluated result. If the request failed, the failure argument will contains an error message. |
Examples
Code Editor (JavaScript)
/** * WARNING: this function transfers data from Earth Engine servers to the * client. Doing so can negatively affect request processing and client * performance. Server-side options should be used whenever possible. * Learn more about the distinction between server and client: * https://developers.google.com/earth-engine/guides/client_server */ // A server-side ee.Date object. var dateServer = ee.Date('2021-4-30'); // Use evaluate to transfer server-side date to the client. The result is // an object with keys "type" and "value" where "value" is milliseconds since // Unix epoch. dateServer.evaluate(function(dateClient) { print('Client-side date is an object', typeof dateClient); print('Object keys include "type" and "value"', Object.keys(dateClient)); print('"value" is milliseconds since Unix epoch', dateClient.value); print('Client-side date in JS Date constructor', new Date(dateClient.value)); });
import ee import geemap.core as geemap
Colab (Python)
# The Earth Engine Python client library does not have an evaluate method for # asynchronous evaluation of ee.Date objects. # Use ee.Date.getInfo() instead.