A point layer must be loaded into ArcMap in order to use this
tool. If your point layer is an event theme and you are experiencing
problems, try making it a shapefile and trying again (right click on the
event theme in the Table of Contents, select Data, then Export Data). The
point layer MUST be in projected coordinate system like UTM or SPC, not a
Geographic (Lat/Lon) coordinate system.
Selected a unique ID field
When you select a point layer from the first drop-down box, all possible unique ID (UID)
fields are listed in the next drop-down box. A UID field will ideally be an integer field,
although the tool can accomodate text (string) fields. Given the choice, select an integer
Using only selected features.
When you select a point layer from the drop down list the program checks to see if
there are selected features in that layer, and enables the "Use selected features
only" option. If you select this option then only the selected features will be
processed. However, you must then pick between two further options. The first option
specifies that distances between points are calculated by referencing ONLY the selected
features. The second option specifies that the distances are calculated by referencing
ALL locations (but only for the selected points). This is a fairly subtle but
important distinction as it has a profound influence on the result.
Listing nearest neighbours.
The nearest neighbour results are output to a separate comma delimited file. Use the "Find the top N closest points (max=100)" number box to define how many points will be listed. If you select just 1 point, then all that will be listed is the single closest point. If you select 5, then the 5 closest points are listed in order of their proximity, with the closest points always occuring first in the list (as you will be able to see from the distances that are also output to that table). Note that in the case of points that are equidistant, one of those points is selected arbitrarily as the closest. Note that the nearest neighbour output file is automatically named based on the folder and file name of the other output table. [Note to programmers: this routine uses the HeapSort method.]
If you have a large number of points, this program may take a considerable amount of time
to run. It is recommended that you try running a test on a smaller sample (e.g. 1000 points)
before embarking on more ambitious analyses.