How do I measure the distance between two points within a country arcmap

Question

I have two shapefiles with points distributed over the whole world. I would like to measure the distance (like the crow flies in km) from each point in shapefile 1 to the closest point from shapefile 2, add all the attributes from the closest point of shapefile2 to the point in shapefile1 but at the same time I have to make sure that these distances are only calculated within the same country. The distance measurement should not cross any borders.

I tried to use the Near option and it gives me partly what I want. It adds all the attributes from the closest point in shapefile2 to the closest point in shapefile1 plus it measures the distance. Now the only problem is that it does not take into account if the two closest points are also in the same country. I would need something like an "if" option for the Near tool. Something like "measure distance to the closest point if country in shapefile 1 = country in shapefile 2". Is there something like that??

Any suggestions?

Answer 1

This is more or less a complete rewrite of my original answer; I was incorrect about what I thought the OP was asking. Given some of the additional information, I would recommend doing something like the following. You could enter it in the python console, or just make a standalone script on the desktop and run it with idle.

import arcpy
arcpy.env.overwrite = True

countries = r"path/to/countries.shp"
pointsA = r"path/to/pointsA.shp"
pointsB = r"path/to/pointsB.shp"

## make feature layers for these datasets
coun = arcpy.management.MakeFeatureLayer(countries,"coun_fl")
ptA = arcpy.management.MakeFeatureLayer(pointsA,"ptA_fl")
ptB = arcpy.management.MakeFeatureLayer(pointsB,"ptB_fl")

## get FIDs of countries that actually intersect with these points
arcpy.management.SelectLayerByLocation(coun,"NEW_SELECTION",ptA)
arcpy.management.SelectLayerByLocation(coun,"ADD_TO_SELECTION",ptB)
fids = [r[0] for r in arcpy.da.SearchCursor(coun,"FID")]

## iterate through FID list, select each country, and then select points
for fid in fids:
    sql = '"FID" = {0}'.format(fid)
    arcpy.management.SelectLayerByAttribute(coun,"NEW_SELECTION",sql)
    arcpy.management.SelectLayerByLocation(ptA,"NEW_SELECTION",coun)
    arcpy.management.SelectLayerByLocation(ptB,"NEW_SELECTION",coun)

    ## now you have only selected points that fall within the same country
    ## you can do whatever operation you want, like
    arcpy.analysis.Near(ptA,ptB)

I don't know how many points you are dealing with, so I'm not sure if this is the speediest way to accomplish what you need. The select processes can be sloooowww sometimes.

You'll still need to check out the projected coordinate systems you use.