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Number of Changes
Script: codes/analysis_4_number_of_changes.js. The calculation is in the function getNumberOfChanges.
Description: Counts how many times the class changed from one year to the next, as the number of runs (blocks of consecutive years with the same class) minus one. Pixels that never changed are masked.
What it shows: It measures landscape dynamism: high values indicate instability or frequent "flipping" between classes. Leaving a class and returning to it counts twice, so a pixel that goes from Forest to Pasture and back to Forest (pixel C in the example) has 2 changes but only 2 classes. Pixel A has 5 changes among 4 classes.
Set at the top of the script; change them before running.
| variable | default | meaning |
|---|---|---|
asset |
Collection 10.1 coverage asset | the multi-band image read by the script |
years |
1985 … 2024 | years included in the series |
bandPrefix |
'classification_' |
band names are bandPrefix + year
|
Besides a land cover reference layer (hidden by default), the script adds:
| layer | value | colors |
|---|---|---|
Number of Changes |
number of changes | light (few) to dark brown (many) |
Pixels with no result are masked and appear transparent.
Copy the whole script into the Google Earth Engine Code Editor, adjust the parameters and click Run. See Home for the example pixels used in the figure.
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