Gillian,
Normally I find that the rowid of the 'buffer' matches that of the original
objects when a whole table has been buffered in one go. However, if you have
been selecting objects or editing the table, this row for row match doesnt
work
(the Rowid ....by the way is the hidden row number in each mapinfo table
you can use it to search and update tables)
as you appear to be buffering points into circles you can try the following:
save a copy of everything you have and then try pasting the following code
into the mapbasic window changing the names of the tables to suit your
copies and follow the instructions in blue:
open your copies, i've called mine 'points' and 'buffs'.
open the mapbasic window (options>>>showmapbasic window)
if you dont have easting and northing columns or an ID column in your
points/buffs table then use the following:
Alter Table "point" ( add east Float,north Float,code Integer ) Interactive
Alter Table "buffs" ( add east Float,north Float,code Integer ) Interactive
Update points Set code = rowid
NOW OPEN one of the files as a map
set coordsys window frontwindow()
Update points Set east = CentroidX(obj)
Update points Set north = Centroidy(obj)
Update buffs Set east = CentroidX(obj)
Update buffs Set north = Centroidy(obj)
Select points.code, buffs.east, buffs.north from buffs, points where
points.east =buffs.east and points.north = buffs.north into mynewbuffs
Browse * From mynewbuffs
Map From mynewbuffs
save mynewbuffs
now add the points file to the mapper and label points in red and buffers in
blue to check
the alter table statements add eastings and northing and a code column to
the table
the update...rowid statement gives a unique id to the points table
the set coordsys statement tells mapinfo to use the map as a reference point
for coordinates (you are probably wanting to use brit nat grid, if you need
lat long then omit the statement)
the update ....east/north clauses set the centoids of the points and buffs
into th etable 9the centroids are the same for points and buffered
points...hence why this works)
the select statement picks the unique points id and one pair of easting and
northing where the centroids of the two files match
the new file now has buffers with an id in common with th epoints
Russell Lawley
Geoscientist
British Geological Survey
www.bgs.ac.uk
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