Sorting a points coordinate list

[psbasha]

Hi ,

I have a list of points and I have to find the boundary nodes from the points.

For example :

pointList = [ [1.2,1.2,10],[10.5,1.3,9.5],[5,0.6,9.8],[1.1,5.0,9.2],[10.1,5.3,8.0]]

How to sort the coordinate values in the list based on X:Xmin,Xmax
Y:Ymin,Ymax,Z: Zmin and Zmax?.Is there any method or function available in Python to sort the list values based on the X ,Y and Z values

Thanks in Advance
PSB

[bvdet]

Hi ,

I have a list of points and I have to find the boundary nodes from the points.

For example :

pointList = [ [1.2,1.2,10],[10.5,1.3,9.5],[5,0.6,9.8],[1.1,5.0,9.2],[10.1,5.3,8.0]]

How to sort the coordinate values in the list based on X:Xmin,Xmax
Y:Ymin,Ymax,Z: Zmin and Zmax?.Is there any method or function available in Python to sort the list values based on the X ,Y and Z values

Thanks in Advance
PSB

The list method sort() will order the list on the first element. If any two first elements are the same, then it looks at the second element. I wrote this function to sort point lists on a given attribute - x, y, or z:

def sortPoints(_ptlist, key='x'):
    try:
        if key.lower() in ['x', 'y', 'z']:
            def cmpItems(a,b):
                return cmp(eval('a.'+key.lower()), eval('b.'+key.lower()))
            _ptlist.sort(cmpItems)
        else:
            raise AttributeError, 'Invalid attribute was passed to sortPoints()'
    except:
        raise TypeError, 'Invalid point list'
 
ptList = [Point(1.0,2.0,3.0), Point(0.5,1.0,7.0), Point(12.6,-12.9,-15.6), Point(-99, 12.6, 1700),\
          Point(29.6, 44.4, 19.1), Point(22.8, 12.2, 4.54)]
 
print formatPtList_("Unsorted points list:", ptList)
 
sKey = "Y"
sortPoints(ptList, sKey)
 
print formatPtList_("Points list sorted on '%s' attribute:" % (sKey), ptList)
 
"""
Unsorted points list:
X attribute         Y attribute         Z attribute         
============================================================
1                   2                   3                   
1/2                 1                   7                   
1'-0 5/8            -1'-0 7/8           -1'-3 5/8           
-8'-3               1'-0 5/8            141'-8              
2'-5 5/8            3'-8 3/8            1'-7 1/8            
1'-10 13/16         1'-0 3/16           4 9/16              
 
Points list sorted on 'Y' attribute:
X attribute         Y attribute         Z attribute         
============================================================
1'-0 5/8            -1'-0 7/8           -1'-3 5/8           
1/2                 1                   7                   
1                   2                   3                   
1'-10 13/16         1'-0 3/16           4 9/16              
-8'-3               1'-0 5/8            141'-8              
2'-5 5/8            3'-8 3/8            1'-7 1/8
"""

You also could get the max and min values for x, y and z:

>>> pointList = [[1.2, 5.0, 9.1999999999999993], [1.2, 5.0, 10], [5, 0.59999999999999998, 9.8000000000000007], [10.1, 5.2999999999999998, 8.0], [10.5, 1.3, 9.5]]
>>> xList = [p[0] for p in pointList]
>>> yList = [p[1] for p in pointList]
>>> zList = [p[2] for p in pointList]
>>> map(max, [xList, yList, zList])
[10.5, 5.2999999999999998, 10]
>>> map(min, [xList, yList, zList])
[1.2, 0.59999999999999998, 8.0]
>>>