This seems like a fairly simple task but I'm struggling to think my way around the problem.
Middle point:
How would I connect these points to form lines by relating the master, previous and next attributes.
Surprisingly tricky indeed, I came up with this, but I'm not sure it's the best way to do it. Now, I am assuming the situation is so complex we can't use the adjacent feature handling in the AttributeManager so I'm doing 2 FeatureJoins to get the previous and next coordinates, then build lines and remove duplicates through a LineCombiner.
@kyle_d_wade
Create a GroupBy column.
Merge the set to itself twice, master=Previous and Master=Next. Make sure to pass the GroupBy value.
Create an attribute like "nr" at merge output of master=Previous give it value 0 and at Master=Next give it value 2. At master itself nr=1.
Sort original set and both merged outputs by GroupBY and nr.
Now use point connector connection break by GroupBy.
The last time I encountered this scenario, I used a connected component graph in python, but I don't think your requirements needs that complicated a structure.
Here's a quick and dirty version that should work, though it will fail if your data references a missing point.
class FeatureProcessor(object):
def __init__(self):
#initialize reference dictionaries
self.FeatureDict={}
self.NeighbourDict={}
def input(self,feature):
#add each feature to the reference dictionaries, key for both is the ID
ID = feature.getAttribute('master')
Next = feature.getAttribute('next')
self.FeatureDict[ID]=feature
self.NeighbourDict[ID]=Next
def close(self):
#search for starting points, could also be previous is None, depending on the data
for id, feature in self.FeatureDict.items():
prev = feature.getAttribute('previous')
if prev == '0':
#create a new line
line = fmeobjects.FMELine()
line.appendPoint(feature.getGeometry())
#find the next vertex and add it to the line, until there are no more vertixes to add
nextId = self.NeighbourDict[id]
while nextId !='0':
geom = self.FeatureDict[nextId].getGeometry()
line.appendPoint(geom)
nextId = self.NeighbourDict[nextId]
#replace the original point geometry with the new line
feature.setGeometry(line)
self.pyoutput(feature)
Basically the same approach as @redgeographics's solution. If resulting lines won't touch each other at their end nodes, you can remove the ListCombiner (from FME Hub) and unset Group By in the LineCombiner.
