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Contributor
Posts: 16
Registered: ‎04-15-2010

# using expression builder to list the distance between points

186 Views, 4 Replies
05-03-2012 04:57 PM

Hello. I have a data table showing points surrounding a central source.

I would like to create a calculation that adds a column in my data table of the points; that shows the distance between each respective point, and the central point.

My knowledge in expression building is limited, and Im hoping someone here could help me.

I assume I would be using some form of calculation using the geom, and the X and Y locations, however Im coming up with nada.

Can anyone help?

Colin

Mentor
Posts: 228
Registered: ‎03-25-2008

# Re: using expression builder to list the distance between points

05-04-2012 11:46 AM in reply to: COLINBIBLE4464

I don't believe you can connect 2 features in a calculation. Therefore you want be able to calculate the distance between. That's what lines are for

How many points are we talking?

Valued Mentor
Posts: 311
Registered: ‎03-24-2004

# Re: using expression builder to list the distance between points

05-04-2012 02:02 PM in reply to: tjmapper

sqrt (x^2 + y^2) = the dist on a 2d plane

if origin is 0,0

then

Sqrt ( Power (  X1 , 2 )  +  Power (  (Y1, 2 ))

so subract x & y of your central point from x1 and y1 of each point

ie origin at 1,1

Sqrt ( Power ( ( X1-1) , 2 )  +  Power (  (Y1-1) , 2 ))

dave

Valued Mentor
Posts: 311
Registered: ‎03-24-2004

# Re: using expression builder to list the distance between points

05-04-2012 02:06 PM in reply to: parkr4st

example i used  UTM83-19 coord sys.  look at the data table. I think this is what you are looking for.

Dave

Contributor
Posts: 16
Registered: ‎04-15-2010

# Re: using expression builder to list the distance between points

05-06-2012 05:34 PM in reply to: parkr4st

Thank you guys.

That was the type of solution that I was looking to implement.

I have 20 points (residences) surrounding a potential site.

I was just measuring the distance from the centre of the proposed site ( a coordinate), to each residence (nodes surrounding the proposed site)

I was writing the distances down and adding them to a spreadsheet. I wanted to shortcut that by having the distances automatically update in the data table if I moved a node (residence). Then I would export the data table into the spreadsheet.

Colin