[Community] Delete item from a LinearRing

[Ari Simmons]

TypeError: 'CoordinateSequence' object doesn't support item deletion

on trying to delete points from a LinearRing (see sample below).

# Remove points indexed in removeList
# Sort the list of indices in reverse order
#so that they can be deleted without throwing off other indices
del(ring.coords[i])

ring.coords is the list of coordinates.. just trying to delete...can this
not be done on a LinearRing?
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[Ari Simmons]

Post by Ari Simmons

['__array_interface__', '__class__', '__del__', '__delattr__',

'__dict__', '__doc__', '__format__', '__geo_interface__', '__geom__',
'__getattribute__', '__hash__', '__init__', '__module__', '__new__',
'__p__', '__reduce__', '__reduce_ex__', '__repr__', '__setattr__',
'__setstate__', '__sizeof__', '__str__', '__subclasshook__', '__weakref__',
'_crs', '_ctypes_data', '_geom', '_get_coords', '_get_geom', '_is_empty',
'_lgeos', '_ndim', '_owned', '_set_coords', '_set_geom', 'almost_equals',
'area', 'array_interface', 'array_interface_base', 'boundary', 'bounds',
'buffer', 'centroid', 'contains', 'convex_hull', 'coords', 'crosses',
'ctypes', 'difference', 'disjoint', 'distance', 'empty', 'envelope',
'equals', 'equals_exact', 'geom_type', 'geometryType', 'has_z', 'impl',
'interpolate', 'intersection', 'intersects', 'is_ccw', 'is_empty',
'is_ring', 'is_simple', 'is_valid', 'length', 'overlaps',
'parallel_offset', 'project', 'relate', 'representative_point', 'simplify',
'symmetric_difference', 'to_wkb', 'to_wkt', 'touches', 'type', 'union',
'within', 'wkb', 'wkt', 'xy']

so, really...I can't delete a coordinate from a LinearRing?

Post by Ari Simmons

TypeError: 'CoordinateSequence' object doesn't support item deletion

on trying to delete points from a LinearRing (see sample below).

# Remove points indexed in removeList
# Sort the list of indices in reverse order
#so that they can be deleted without throwing off other indices
del(ring.coords[i])

ring.coords is the list of coordinates.. just trying to delete...can this
not be done on a LinearRing?

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[Sean Gillies]

Hi Ari,

No, you can't delete an item like that (by design), but you can reassign to

Post by Ari Simmons

Post by Ari Simmons

from shapely.geometry import Point
p = Point(0, 0)
list(p.coords)

[(0.0, 0.0)]

Post by Ari Simmons

Post by Ari Simmons

p.wkt

'POINT (0 0)'

Post by Ari Simmons

Post by Ari Simmons

p.coords = [(1,1)]
list(p.coords)

[(1.0, 1.0)]

Post by Ari Simmons

Post by Ari Simmons

p.wkt

'POINT (1 1)'

I hope this helps,

Post by Ari Simmons

Post by Ari Simmons

['__array_interface__', '__class__', '__del__', '__delattr__',

'__dict__', '__doc__', '__format__', '__geo_interface__', '__geom__',
'__getattribute__', '__hash__', '__init__', '__module__', '__new__',
'__p__', '__reduce__', '__reduce_ex__', '__repr__', '__setattr__',
'__setstate__', '__sizeof__', '__str__', '__subclasshook__', '__weakref__',
'_crs', '_ctypes_data', '_geom', '_get_coords', '_get_geom', '_is_empty',
'_lgeos', '_ndim', '_owned', '_set_coords', '_set_geom', 'almost_equals',
'area', 'array_interface', 'array_interface_base', 'boundary', 'bounds',
'buffer', 'centroid', 'contains', 'convex_hull', 'coords', 'crosses',
'ctypes', 'difference', 'disjoint', 'distance', 'empty', 'envelope',
'equals', 'equals_exact', 'geom_type', 'geometryType', 'has_z', 'impl',
'interpolate', 'intersection', 'intersects', 'is_ccw', 'is_empty',
'is_ring', 'is_simple', 'is_valid', 'length', 'overlaps',
'parallel_offset', 'project', 'relate', 'representative_point', 'simplify',
'symmetric_difference', 'to_wkb', 'to_wkt', 'touches', 'type', 'union',
'within', 'wkb', 'wkt', 'xy']
so, really...I can't delete a coordinate from a LinearRing?

Post by Ari Simmons

TypeError: 'CoordinateSequence' object doesn't support item deletion

on trying to delete points from a LinearRing (see sample below).

# Remove points indexed in removeList
# Sort the list of indices in reverse order
#so that they can be deleted without throwing off other indices
del(ring.coords[i])

ring.coords is the list of coordinates.. just trying to delete...can this
not be done on a LinearRing?

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[Mike Toews]

The best way to remove coordinates from a coordinate sequence is to
extract the coordinates as a regular Python list, then use the
built-in list methods to delete/modify the list of coordinates, and
then generate a new Shapely geometry. e.g.

from shapely.geometry import LinearRing
from shapely.wkt import loads
lr = loads('LINEARRING (0 0, 0 1, 1 1, 1 0, 0 0)')
lrc = lr.coords[:] # extract coordinates
del lrc[2] # delete the third coordinate
lr2 = LinearRing(lrc) # make a new geometry
lr2.wkt # 'LINEARRING (0 0, 0 1, 1 0, 0 0)'

-Mike

Post by Ari Simmons

TypeError: 'CoordinateSequence' object doesn't support item deletion

on trying to delete points from a LinearRing (see sample below).

# Remove points indexed in removeList
# Sort the list of indices in reverse order
#so that they can be deleted without throwing off other indices
del(ring.coords[i])

ring.coords is the list of coordinates.. just trying to delete...can this
not be done on a LinearRing?
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