Retrieving all Faces for each Node in a femmesh

[hdbondt]

Given a Femmesh I'm trying to build a python dictionary which contains a list of faces for each node in the femmesh.
This list is made of faces which have the respective node in FemMesh.getElementNodes(face)

below is my femmesh with 1392 nodes

========================== Dump contents of mesh ==========================

1) Total number of nodes: 1392
2) Total number of edges: 101
3) Total number of faces: 488
4) Total number of polygons: 0
5) Total number of volumes: 651
6) Total number of polyhedrons: 0


but:

Code: Select all

len(np.unique([[id for id in femmesh.getElementNodes(f)] for f in femmesh.Faces]))

returns 978

From which I think that 1392-978=414 nodes do not belong to a face.
But when I highlight these nodes, I see them on the FEMMesh.

which means that 414 nodes in my dictionary have an empty list of faces.

[bernd]

Would you post your FEMMesh?

[hdbondt]

Would you post your FEMMesh?

[bernd]

when I load your file and run the following code I get an error:

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import numpy as np
femmesh = App.ActiveDocument.getObject("FEMMeshGMSH001").FemMesh
len(np.unique([[id for id in femmesh.getElementNodes(f)] for f in femmesh.Faces]))

Code: Select all

>>> 
>>> import numpy as np
>>> femmesh = App.ActiveDocument.getObject("FEMMeshGMSH001").FemMesh
>>> len(np.unique([[id for id in femmesh.getElementNodes(f)] for f in femmesh.Faces]))
Traceback (most recent call last):
  File "<input>", line 1, in <module>
  File "/usr/lib/python2.7/dist-packages/numpy/lib/arraysetops.py", line 166, in unique
    return np.sort(list(set(ar)))
TypeError: unhashable type: 'list'
>>> 

Would you post the code you used to get the 978

[bernd]

Given a Femmesh I'm trying to build a python dictionary which contains a list of faces for each node in the femmesh.

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femmesh = App.ActiveDocument.getObject("FEMMeshGMSH001").FemMesh
nodefaces = {}
for k in femmesh.Nodes.keys():
    nodefaces[k] = []

for n in nodefaces:
    for f in femmesh.Faces:
        if n in femmesh.getElementNodes(f):
            nodefaces[n].append(f)

[bernd]

BTW:

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for i in nodefaces.items():
    if not i:
        print("found node without faces")

returns:

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>>> 
>>> for i in nodefaces.items():
...     if not i:
...         print("found node without faces")
... 
>>> 

means all nodes have at least one face ...

[hdbondt]

BTW:

Code: Select all

for i in nodefaces.items():
    if not i:
        print("found node without faces")

returns:

Code: Select all

>>> 
>>> for i in nodefaces.items():
...     if not i:
...         print("found node without faces")
... 
>>> 

means all nodes have at least one face ...

Not really, items() returns a tuple of key/value pair from the dictionary.
if you run:

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for n in nodefaces.items():
    print(n)

the output will be:
...
(1377L, [])
(1378L, [])
(1379L, [])
(1380L, [])
(1381L, [])
(1382L, [])
(1383L, [])
(1384L, [])
(1385L, [])
(1386L, [])
(1387L, [])
(1388L, [])
(1389L, [])
(1390L, [])
(1391L, [])
(1392L, [])

As you see the last nodes have an empty list, no faces.

when I load your file and run the following code I get an error:

...

Would you post the code you used to get the 978

When I run the code it works in my version of FreeCAD.
I don't understand why there is different behaviour, but I rewrote the code to have a flat list instead of a nested one.
Please try again.

Code: Select all

import numpy as np
femmesh = App.ActiveDocument.getObject("FEMMeshGMSH001").FemMesh
len(np.unique([id for f in femmesh.Faces for id in femmesh.getElementNodes(f) ]))

This should give the same output (978)

I think I found something which could explain the output (978)

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shape = App.ActiveDocument.Fusion001001.Shape
len(np.unique(( [ node_ids for f in shape.Faces for node_ids in (femmesh.getNodesByFace(f))])))

also returns 978

on an unrelated note:
My part is called Fusion001001, which, for code clarity, is not a good name.
But when I rename the part in the project (using F2 or right click rename) the label changes but the name used to acces the shape through code stays the same. Is this intended behavior?
When I change the label, it changes in the property view, but there's no code generated in the python console, maybe that's the problem?

[bernd]

on an unrelated note:
My part is called Fusion001001, which, for code clarity, is not a good name.
But when I rename the part in the project (using F2 or right click rename) the label changes but the name used to acces the shape through code stays the same. Is this intended behavior?
When I change the label, it changes in the property view, but there's no code generated in the python console, maybe that's the problem?

Yes it is intended. The name in FreeCAD is unique and can not be changed AFAIK. Rename (F2) changes the label of an object. The label and the name are two different properties of an object.

[bernd]

@hdbondt: You are right ... on your file it gives lots of nodes without faces ...

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femmesh = App.ActiveDocument.getObject("FEMMeshGMSH001").FemMesh
nodefaces = {}
for k in femmesh.Nodes.keys():
    nodefaces[k] = []

for n in nodefaces:
    for f in femmesh.Faces:
        if n in femmesh.getElementNodes(f):
            nodefaces[n].append(f)

count = 0
for n in nodefaces.items():
    if not n[1]:
        # print(n)
        count += 1

print(count)

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...
414

Mhh strange ...

[bernd]

Code: Select all

import numpy as np
femmesh = App.ActiveDocument.getObject("FEMMeshGMSH001").FemMesh
len(np.unique([id for f in femmesh.Faces for id in femmesh.getElementNodes(f) ]))

This should give the same output (978)

I get 978 too.

another version would be ...

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ids = []
for f in femmesh.Faces:
    for id in femmesh.getElementNodes(f):
        ids.append(id)

len(set(ids))

result will be 978 too