I want to calculate the coordinates of the center point of a line with 2 points (begin and end point). The resulting coordinate (x,y) should be stored in two attributes, i.e. x_middle and y_middle.
I've solved it with a series of transformers, but that's not very elegant. Perhaps somebody has an idea if there's a more easier way to do this.
Kind regards
Thomas
1) You don't need to calculate diffs.
x_middle = (_x_begin + _x_end) * 0.5
y_middle = (_y_begin + _y_end) * 0.5
2) The center of a line segment is equal to the center of its bounding box, so you can calculate the (x, y) based on the bounds coordinates that can be extracted with the BoundsExtractor.
x_middle = (_xmin + _xmax) * 0.5
y_middle = (_ymin + _ymax) * 0.5
3) The two expressions can be performed by an AttributeCreator.
Conclusion.
You can replace those transformers with a BoundsExtractor and an AttributeCreator.
Takashi
If you use @Coordinate function, just one AttributeCreator is enough.
See here to learn more about FME Functions.
FME and Factory and Function Documentation (http://docs.safe.com/fme/html/FME_FactFunc/index.html)
Snippingmode: percentage.
Start:50
End:50
this gives you the centerpoint of the line.
Extract coordinates if needed.
What I don't understand is why the functions @Coordinate and @Evaluate don't show up in the menu of my arithmetic editor. Shouldn't they be selectable from the left list? With manual inserting it works however.
Kind regards
Thomas
Thank you Gio!
Almost all the FME functions are wrapped with transformers. For example, the CoordinateExtractor internally calls @Coordinate function; the BoundsExtractor calls @Bounds function.
If you are interested in the internal of transformers, look at this file in your system with a text editor. But, be careful not to destroy the file!
<FME HOME>\\transformers\\fmesuite.fmx
Since transformers can be used easier and safer than using FME functions directly, probably Safe intends to recommend users to use transformers unless there is a specific reason. The situation is similar to Python/Tcl use.
I think that's why only few functions are shown in the Arithmetic Editor.
And it is also the reason that I suggested BoundsExtractor+AttributeCreator first ;)
Takashi
This could also be achieved with the CentrePointExtractor.
This could also be achieved with the CentrePointExtractor.