Hey Keegan,

if the question "Is 'John's House' within 10km of point A?" is the key issue then I could proposed following: Obviously you know the attribute you are asking for ("John's House") and obviosly you know about the position of point A. Then the solution is a simple distance with the threshold of 10 km, isn't it? Is the distance smaller or qual 10km returm "TRUE" if not return "FALSE". So far the logic to provide the answer to the question.

You can simply get the coordinates of the point A. For feature, which is not a point you can get the coordinates of all nodes. Then you create a loop for the distance calculation from A to each of the nodes.

How to select the layer by attribute via python you'll find here:http://resources.arcgis.com/en/help/main/10.1/index.html#//001700000071000000

And here some hints on recording, if you going to use interactive point selection:

http://help.arcgis.com/en/arcgisdesktop/10.0/help/index.html#//002z0000001n000000

and here a small python snippet to play around:

import math

A = [0,0] ### point of interest A

threshold = 10.0 ### the distance to prove

houses = [[2, 3], [11,5], [8,3]] ### nodes of a feature John's house

### loop calculate distance from A to each point in houses

count = 0

for i in range (len(houses)):

dist = math.sqrt(math.pow((A[0]- houses[i][0]),2) + math.pow((A[1]- houses[i][1]),2))

if dist

behind of this problem you have some theorical issues:

a) First of all if you want to have consistent results you need to verified if your data or analysis is being made in a correct cartographic reference systems (crs). A common crs is utm and the zone will depend of your longitude.

b) you must check if your units of measure. are thiose meters, miles, kilometers? Have you take in account a unit conversion procedure from input data to kilometers?

c) When you make a search by a radius like 10 km, you have different situations:

1. the objects lie completely inside the area

2. Objects don 't completely lie inside the area

3. Objects touch the search area.

4. objects absolutely don't lie in the search area

In your analysis you must take in account that search parameters change in the three first cases.

d) with arcgis you can do this search in differents ways ordered by low to higher complexity

1- by using a buffer tool. You will find it at the toolbox

2- you can try make the analysis using mm-sql (lots of examples in internet)

3- use python or model builder ( this can generate a python code output)

Thank you both for your answers! After a good night's sleep, and reading over your responses, I have some more inspiration to go on.

Gabriel - thank you for your checklist, it's always good to make sure. My data are already projected in UTM (our zone is 20), and I'm expressing my units in metres - I wrote in km here for brevity. As for the topology of objects in my radius, I'm looking for points - which simplifies it to "inside zone and/or on boundary" OR "outside the zone".

Moving forward, I'll probably use python for its flexibility - I have a method written using buffers, but it's more processing-intensive, and I'm looking for something that can quickly and automatically iterate through a list of target objects.

Jewgenij - thank you for your advice and sample code. The features that I'm looking for ("houses") are point data (our scale is very large), which simplifies things a lot. Having said that, your loop structure is excellent for non-point features, and we may include such features at a more advanced stage in our analysis - lakes, urban areas, etc.

And your code got me thinking... rather than ending the function in "print string", I will continue on with it to have it pass us the necessary information. So, if an object is within the search radius, I'll have it return the distance and bearing from A to House (I've already written a separate function to calculate these, so it's a simple job to tack them on). If working in arcpy, I can have it add fields to the attribute table for each of these, thus adding to the entry for A. Then the user can be given an output form containing the relevant details.

Thanks again for the help, and I'll keep you posted on my solution as it develops.

All the best,

Keegan