How to write feature class attributes without „null-values“?

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Dear FME-users,

I’m creating polygons from input raster data. Therefore I use the transformer “RasterToPolygonCoercer”. The values of 7 input data are written in 1 output feature class.

These attributes includes a lot of “null-values”. (<NULL>)

Do you’ve any ideas which transformer can solve it?

Thank you very much and best regards.

Konrad

Answer 1 · 2017-05-15T16:48:46Z

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Answer by takashi · May 15, 2017 at 04:48 PM

OK, if I understood the requirement correctly, the AreaOnAreaOverlayer (Accumulation Mode: Merge Incoming Attributes) is what you are looking for to merge cell values on the same area. If you created points with the RasterCellCoercer, the Matcher (SingleMatched output port) can be used instead.
In both cases, before merging, the name of attribute that stores the cell value should be renamed appropriately to differentiate the source raster.

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uba_kp · May 15, 2017 at 05:27 PM 0

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It works with the "AreaOnAreaOverlayer", thank you so much @takashi! :)

Answer 2 · 2017-05-15T14:25:42Z

Answer by uba_kp · May 15, 2017 at 02:25 PM

I’ve 7 input data with the same extension. It means that the values are different. Later I want to do queries for point coordinates (x, y). For this I need 7 values and not just 1 and 6 times “Not Null”.

Maybe I can create 7 single output files and set them in relation. But I don’t know how to do this.

I hope my description is understandable. If not I’ll try it again.

Thank you very much. :)

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takashi · May 15, 2017 at 03:10 PM 1

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If you just need to the get cell values on the location (x, y) of a specific point from the rasters, you can use the PointOnRasterValueExtractor.
However, I cannot understand why you got null values from raster cells. Every raster cell always has a value, never contains the null. How did you get the nulls?

uba_kp takashi · May 15, 2017 at 03:23 PM 0

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I've transformed the raster data to vector data with the transformer "RasterToPolygonCoercer". The reason why I get the nulls is that I've several input data and 1 output data. I don't have nulls when I decide to make the same number as output like the input.

takashi · May 15, 2017 at 03:34 PM 1

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I suspect you didn't merge attributes of the seven same shape polygons created by the RasterToPolygonCoercer transformer into a single feature.
Can you show us the screenshot of your Main canvas?
One more question. The RasterToPolygonCoercer creates exactly same shape polygon from the seven source rasters?

Answer 3 · 2017-05-15T13:54:07Z

Answer by takashi · May 15, 2017 at 01:54 PM

If you need to change all the null values to any specific value, I believe that the NullAttributeMapper transformer is the way to go.

I'm unclear what the "overlapping polygons" means. Could you please elaborate the requirement?

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Answer 4 · 2017-05-15T13:20:22Z

Answer by uba_kp · May 15, 2017 at 01:20 PM

Do you've an idea how to fill the attribute values of the overlapping polygons?

I've added a screenshot, please take a look in the attachment.

17-05-12-fme-null.png (6.8 kB)

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Answer 5 · 2017-05-12T13:15:54Z

Answer by david_r · May 12, 2017 at 01:15 PM

Have you looked at the NullAttributeMapper?

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uba_kp · May 12, 2017 at 01:19 PM 0

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Yes I did. But it does not work. Do you know which adjustments I've to set?

david_r uba_kp · May 12, 2017 at 01:30 PM 1

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Did you read the documentation?
It would be helpful if you could give us a concrete example of what doesn't work the way you expect it to.

uba_kp · May 12, 2017 at 01:36 PM 0

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It seems I've to use the option "New Value". Do you know what I can fill in? Maybe "@CurrentAttribute()"?

david_r uba_kp · May 12, 2017 at 01:43 PM 1

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What would you like there to be in place of NULL values?

uba_kp david_r · May 15, 2017 at 01:44 PM 0

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Sorry I did not see your answer. I'd like to have the values of the overlapping polygons from the other attributes.

How to write feature class attributes without „null-values“?

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