Query vector data intersections

Question

Hello All,

I am a student and I am trying to locate "at risk" harbors around Alaska from polluted drainage by mines via river inflow.  What I would like to do is quantify how many tributaries a specific river inflow represents.  They rivers are nothing more than lines in a .shp file so how can I how analyze this?  Is there a way to query the number of intersections between endpoints of one tributary and the line of another?

Regards,
John

DanPatterson_Retired · Answer

Query the for the rivers, export to a shapefile....query for the line(s) of interest, export to shapefile, then intersect ....you can intersect a file with itself, then you have to query out from there...the former alternative is the cleanest and should take under a minumte

SepheFox · Answer

Hmmm, from his description I get the impression that it's just one shapefile. So how would you tackle that problem? I couldn't think of any easy way.

DanPatterson_Retired · Answer

If the two are indeed separate files, then perform an intersect analysis which will yield your intersection points if the segments do indeed cross as shown in the examples for line-line intersection.  This will at least give you the starting point.  There are alternatives involving code, however, I think this approach will enable you to use Select by Location, Spatial Join etc to obtain the associations and information between the resultant points and the crossing feature.