I have a continuous raster with cell values between 0 and 100. I want to reclassify these values to 5 classes:
For example everything between 90 and 100 should have the new cell value 1.
I do not know how to extract the cell values to make them accessible for the conditional comparison.
In the screenshot you can see my current approach. The problem is @CurrentAttribute() which is the wrong choice to extract the cells.
What's the correct way to extract the cell value?
Best answer by jdh
I don't think you can do this with a single RasterCellValueReplacer (RCVR).
Either chain as many RCVR as you have classes, making sure the new value isn't in the range of any of the subsequent classes.
Or use a RasterExpressionEvaluator with nested conditionals
if (A[0] >90, 1, if (A[0]>80, 2, if (A[0]>10, 3,0)))
+28I don't think you can do this with a single RasterCellValueReplacer (RCVR).
Either chain as many RCVR as you have classes, making sure the new value isn't in the range of any of the subsequent classes.
Or use a RasterExpressionEvaluator with nested conditionals
if (A[0] >90, 1, if (A[0]>80, 2, if (A[0]>10, 3,0)))
I don't think you can do this with a single RasterCellValueReplacer (RCVR).
Either chain as many RCVR as you have classes, making sure the new value isn't in the range of any of the subsequent classes.
Or use a RasterExpressionEvaluator with nested conditionals
if (A[0] >90, 1, if (A[0]>80, 2, if (A[0]>10, 3,0)))
Thanks! However, this does not work quite yet – I have either the new class 1 or 0 (NoData). It never gets into class 2 or 3 even though it should be getting there according to the source data.
+28Thanks! However, this does not work quite yet – I have either the new class 1 or 0 (NoData). It never gets into class 2 or 3 even though it should be getting there according to the source data.
Which option are you using?
+28Like this, with RasterExpressionEvaluator
Could you provide your full expresion
+28Could you provide your full expresion
The following expression matches your original conditionals:
if (A[0]>=@Value(A:Suburban)&&A[0]<@Value(A:Residential),1,if (A[0]>=@Value(A:Urban)&&A[0]<@Value(A:Suburban),2,if (A[0]>=@Value(A:DenseUrban)&& A[0]< @Value(A:Urban),3,if(A[0]<@Value(A:DenseUrban),4,0))))
but if you don't have data above your residential value it can be simplified to
if (A[0]>=@Value(A:Suburban,1,if (A[0]>=@Value(A:Urban),2,if (A[0]>=@Value(A:DenseUrban,3,4)))
The following expression matches your original conditionals:
if (A[0]>=@Value(A:Suburban)&&A[0]<@Value(A:Residential),1,if (A[0]>=@Value(A:Urban)&&A[0]<@Value(A:Suburban),2,if (A[0]>=@Value(A:DenseUrban)&& A[0]< @Value(A:Urban),3,if(A[0]<@Value(A:DenseUrban),4,0))))
but if you don't have data above your residential value it can be simplified to
if (A[0]>=@Value(A:Suburban,1,if (A[0]>=@Value(A:Urban),2,if (A[0]>=@Value(A:DenseUrban,3,4)))
It still does not really work.
I attached a sample raster, do you achieve a classification into 5 classes with RasterExpressionEvaluator?
freiflaeche.tif
+28It still does not really work.
I attached a sample raster, do you achieve a classification into 5 classes with RasterExpressionEvaluator?
freiflaeche.tif
Put a RasterBandNodataRemover before the RasterExpressionEvaluator.
Bad things happen when there is a NoData value set.
I would use the expression
if (A[0]==0,0,if (A[0]>=@Value(A:Suburban,1,if (A[0]>=@Value(A:Urban),2,if (A[0]>=@Value(A:DenseUrban,3,4))))
and then you can use a RasterBandNoDataSetter to put back the NoData.
Put a RasterBandNodataRemover before the RasterExpressionEvaluator.
Bad things happen when there is a NoData value set.
I would use the expression
if (A[0]==0,0,if (A[0]>=@Value(A:Suburban,1,if (A[0]>=@Value(A:Urban),2,if (A[0]>=@Value(A:DenseUrban,3,4))))
and then you can use a RasterBandNoDataSetter to put back the NoData.
great thanks!
this works :-)
just found out about NoData too in this article: https://knowledge.safe.com/articles/1221/elevation-zoning-scenario.html
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