AI-generated Key Takeaways
-
The
remapfunction maps input values to output values using two parallel lists. -
Unmatched input values are either set to a default value if provided or masked out.
-
Floating point precision errors might prevent exact matches for floating point values.
-
The
fromandtolists must have the same number of values for the remapping to work correctly. -
You can specify a
defaultValueto handle values not present in thefromlist and abandNameto target a specific band.
| Usage | Returns |
|---|---|
Image.
remap
(from, to, defaultValue
, bandName
)
|
Image |
| Argument | Type | Details |
|---|---|---|
|
this:
image
|
Image | The image to which the remapping is applied. |
from
|
List | The source values (numbers or ee.Array). All values in this list will be mapped to the corresponding value in 'to'. |
to
|
List | The destination values (numbers or ee.Array). These are used to replace the corresponding values in 'from'. Must have the same number of values as 'from'. |
defaultValue
|
Object, default: null | The default value to replace values that weren't matched by a value in 'from'. If not specified, unmatched values are masked out. |
bandName
|
String, default: null | The name of the band to remap. If not specified, the first band in the image is used. |
Examples
Code Editor (JavaScript)
// A land cover image. var img = ee . Image ( 'ESA/WorldCover/v100/2020' ); // A list of pixel values to replace. var fromList = [ 10 , 20 , 30 , 40 , 50 , 60 , 70 , 80 , 90 , 95 , 100 ]; // A corresponding list of replacement values (10 becomes 1, 20 becomes 2, etc). var toList = [ 1 , 2 , 2 , 2 , 3 , 2 , 4 , 5 , 6 , 6 , 2 ]; // Replace pixel values in the image. If the image is multi-band, only the // remapped band will be returned. The returned band name is "remapped". // Input image properties are retained in the output image. var imgRemap = img . remap ({ from : fromList , to : toList , defaultValue : 0 , bandName : 'Map' }); // Display the original and remapped images. Note that similar land cover // classes in the original image are grouped into aggregate classes by // from → to value mapping. Map . addLayer ( img , null , 'Original image' ); Map . addLayer ( imgRemap , { min : 1 , max : 6 , palette : 'darkgreen, lightgreen, red, white, blue, lightblue' }, 'Remapped image' );
import ee import geemap.core as geemap
Colab (Python)
# A land cover image. img = ee . Image ( 'ESA/WorldCover/v100/2020' ) # A list of pixel values to replace. from_list = [ 10 , 20 , 30 , 40 , 50 , 60 , 70 , 80 , 90 , 95 , 100 ] # A corresponding list of replacement values (10 becomes 1, 20 becomes 2, etc). to_list = [ 1 , 2 , 2 , 2 , 3 , 2 , 4 , 5 , 6 , 6 , 2 ] # Replace pixel values in the image. If the image is multi-band, only the # remapped band will be returned. The returned band name is "remapped". # Input image properties are retained in the output image. img_remap = img . remap ( from_list , to_list , defaultValue = 0 , bandName = 'Map' ) # Display the original and remapped images. Note that similar land cover # classes in the original image are grouped into aggregate classes by # from → to value mapping. m = geemap . Map () m . add_layer ( img , None , 'Original image' ) m . add_layer ( img_remap , { 'min' : 1 , 'max' : 6 , 'palette' : [ 'darkgreen' , 'lightgreen' , 'red' , 'white' , 'blue' , 'lightblue' , ], }, 'Remapped image' , ) m
