Problem with merge because of -round- function

[Mathias Imboden]

Hello,

I'm trying to merge two datasets using GPS data (latitude and longitude) as ID. On the first dataset, the GPS data is like this : -1.467934012413. On the other one, like this : -1.5.

In order to be able to merge the datasets, i tried to round the observations from the first dataset using:

replace lon_mod=round(lon_mod, 0.1)
replace lat_mod=round(lat_mod, 0.1)

At first I thought it worked fine, but when I tried to perform the merge, I realized that observations that should have matched didn't.

I think the problem comes from the round function, because when I use dataex, it shows that some observations are not quite rounded. I read on another thread that it was a common phenomen and a matter of format, but I couldn't find how to fix the problem in my case.

* Example generated by -dataex-. For more info, type help dataex
clear
input double(lat_mod lon_mod)
               -1.5 29.900000000000002
-1.4000000000000001 29.900000000000002
-1.4000000000000001 29.900000000000002
-1.4000000000000001 29.900000000000002
-1.4000000000000001 29.900000000000002
-1.4000000000000001 29.900000000000002
-1.4000000000000001 29.900000000000002
-1.4000000000000001 29.900000000000002
-1.4000000000000001 29.900000000000002
-1.4000000000000001 29.900000000000002
-1.4000000000000001 29.900000000000002
-1.4000000000000001 29.900000000000002
-1.4000000000000001                 30
               -1.3               29.8
               -1.3               29.8
               -1.3               29.8
               -1.3               29.8
               -1.3               29.8
               -1.3               29.8
               -1.3               29.8
               -1.3               29.8
               -1.3               29.8
               -1.3               29.8
               -1.3               30.1
               -1.3               30.1
end

How can I make these observations perfectly rounded si I can perform the merge?

Thanks,

Mathias Imboden

[Ken Chui]

There is probably a "light path" to fix this. Here is what I think a "dark" one. Change them into string:

tostring lat_mod, gen(lats) force
tostring lon_mod, gen(lons) force

Then, merge by the string lat and long.

[Mathias Imboden]

Thank you, I did what you suggested and it worked fine.