Hello!
I need to randomly select 7 grids from the grid net including condition that selected grids cannot be self-intersecting and cannot overlap each other. See image below.
How to approach it in the most efficient way?
Solved
Random grid selection
Best answer by ebygomm
And because looping blocking transformers are so horrible to work with an alternative solution using a spatial relator and some python
import fme
import fmeobjects
import random
class chooseSquares(object):
def __init__(self):
#create blank list
self.mylist=[]
def input(self,feature):
#build list containing feature, id and relationships
id = feature.getAttribute('_count')
touches = feature.getAttribute('_relationships{}._count')
self.mylist.append((feature,id,touches))
def close(self):
for x in range(0,7):
#shuffle list
random.shuffle(self.mylist)
#choose grid from first feature inlist
newfeature = self.mylist[0][0]
#get features that interact
exclude = self.mylist[0][2]
#remove from list any features that intersect chosen gridsquare
self.mylist = [(f,i,r) for f,i,r in self.mylist if str(i) not in exclude]
#outputchosengridsquare
self.pyoutput(newfeature)
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+62- Celebrity
Use a Sampler to randomly grab one tile, then a SpatialFilter to select all tiles not touching that randomly selected tile. Then use that result set as the input for the next iteration, and so on.
I've done 2 iterations here, you can simply copy & paste the rest, or try and do it through looping in a custom transformer.
+46- Influencer
Looping transformers in FME are fairly horrible to work with when you've got blocking transformers, but it can be done. This is more or less the same workflow as @redgeographics within the transformer but just handles the looping
+46- Influencer
- Best Answer
And because looping blocking transformers are so horrible to work with an alternative solution using a spatial relator and some python
import fme
import fmeobjects
import random
class chooseSquares(object):
def __init__(self):
#create blank list
self.mylist=[]
def input(self,feature):
#build list containing feature, id and relationships
id = feature.getAttribute('_count')
touches = feature.getAttribute('_relationships{}._count')
self.mylist.append((feature,id,touches))
def close(self):
for x in range(0,7):
#shuffle list
random.shuffle(self.mylist)
#choose grid from first feature inlist
newfeature = self.mylist[0][0]
#get features that interact
exclude = self.mylist[0][2]
#remove from list any features that intersect chosen gridsquare
self.mylist = [(f,i,r) for f,i,r in self.mylist if str(i) not in exclude]
#outputchosengridsquare
self.pyoutput(newfeature)