Dear All,
Thank you very much to all who replied, trying to help: Trey Pattillo, =
Tim Nuteson and Derek Snyder
Briefly the subject was:
Working with a street layer I would like to create objects for each =3D
street intersection point
The best solution came from Trey Pattillo:
The method I have used is slow, as it iterates thru the street list and =
uses
the FIND command to look for the intersections, just like in the Ctrl+F.
1) Create the table to hold your "finds" and make it editable
This can be done in code
2) build a list of unique street names into 2 variables
Select * from StreetTable Group By Street Order By Street Into =
Street1
Select * from Street1 Into Street2
3) set up FIND USING
Find Using StreetTable(Street)
4) loop thru Street1 and see if Street2 intersects it [cmd_info_x,
cmd_info_y] when Cmd_Info_Find_RC > 0
get the x and y and put in map
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D CODE SAMPLE =
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
Dim aObj as Object
Dim LookFor As String
Create Table "Intersect" (Street1 Char(30), Street2 Char(30)) File
"C:\MapInfo\Data\Intersect.tab" TYPE DBF
Create Map For Intersect
Select * from StreetTable Group By Street Order By Street Into Street1
Select * from Street1 Into Street2
Find Using StreetTable(Street)
Fetch First From Street1
while not eot(Street1)
Fetch First From Street2
While not eot(Street2)
LookFor=3DStreet1.Street+" && "+Street2.Street
Find LookFor
If CommandInfo(CMD_INFO_FIND_RC)>0 then
aObj=3DCreatePoint Into Variable aObj (CMD_INFO_X, =
CMD_INFO_Y)
MakeSymbol(33,12,0)
Insert Into IntersectionTable (Street1,Street2,obj) Values
(Street1.Street,Street2.Street,aObj)
End If
Fetch Next From Street2
Wend '' street2
Fetch Next From Stree1
Wend '' street1
undim aObj
undim LookFor
The following was suggested by Derek Snyder
Create Objects As Intersect produces a result of that space that is the
intersection of ALL of the objects, not any 2 objects.
What you probably want to use is Objects Intersect. Use the input table =
as
both the selection. This should give you what you want.
Another alternative is to use the IntersectNodes() MapBasic function. =
This
only takes 2 objects at a time, so it is a bit more cumbersome. But, it
will work with Line and Polyline objects as input, so you won't need to =
do
the buffer step.
Finally I add my code (inspired from Trey Pattillo's code), adjusted to =
suit my needs:
Sub GenerateIntersections
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D CODE SAMPLE =
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
Dim aObj as Object
Dim szLookFor as String
Dim szStr1, szStr2 as String
Dim fLon, fLat as Float
Dim snNumStr1, snI, snJ as Smallint
Select * from SourceTab Group By StreetName Order By StreetName Into =
Street1
snNumStr1=3DTableInfo(Street1, TAB_INFO_NROWS)
Select * from Street1 Into Street2
Find Using SourceTab(StreetName)
For snI=3D1 to snNumStr1
fetch rec snI from Street1
szStr1=3DStreet1.StreetName
For snJ=3D1 to snNumStr1 '* Table Street1 and Street2 have the
same =
number of records
Fetch rec snJ From Street2
szStr2=3DStreet2.StreetName
If szStr1<>szStr2 Then '* Remove self-intersection cases
szLookFor=3DszStr1+" && "+szStr2
Find szLookFor
If CommandInfo(CMD_INFO_FIND_RC)=3D1 then '* consider
only "exacy =
match" cases
fLon=3DCommandInfo(CMD_INFO_X)
fLat=3DCommandInfo(CMD_INFO_Y)
aObj=3DCreatePoint(fLon, fLat)
Insert Into DestTab (Street1,Street2,obj)
Values(szStr1,szStr2,aObj)
End If
End If
Next
Print ">>>Lap "+snI+"<<<" '* Just to see the progress
Next
End Sub
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D END CODE SAMPLE =
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
NOTE:
The resulting table (DestTab) will contain duplicated points for each =
intersection.
This can be removed by running two queries:
Select Street1, Street2, CentroidX(obj), CentroidY(obj) from DestTab =
into IntersCoord
Select * from IntersCoord Group by COL3, COL4 into IntersGRP
Save the table IntersGRP and then create points using COL3, COL4.
Mircea Baila
MobiFon, Romania
E-mail: [EMAIL PROTECTED]
Web: www.connex.ro
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