I received a dataset that had the coordinates for Latitude and longitude broken up in different fields. There's a LAT_DEGREE field and a LAT_MINUTES field.

I've collated them into a single field for display, assuming I'm working with DMS coordinates- but when I bring the csv into arcmap the two new STRT_LAT and STRT_LONG fields are not present within the dropdown table of the Display XY Data tool.

I'm a bit confused, as this tool is not usually very picky, and will literally allow you to input any field you want no matter how wrong they may be. The fields are viewable when I open the table, but not through the Add XY Data option.

Any ideas?

Table Example

  • It could be a "type" issue. Are the values in the fields possibly string (seems likely since there is a space)? – jbchurchill Mar 28 '17 at 17:42
  • 1
    The field is probably being interpreted as a string/text and needs to be numeric/double. You should create two new fields lng and lat and convert the DMS to DD. – artwork21 Mar 28 '17 at 17:42
  • Are you sure those lat/long values are in DMS? They looks like degrees, decimal minutes to me. – Dan C Mar 28 '17 at 18:16
  • @Dan C - I thought the OP understood that they were in Decimal Minutes but rereading the question I'm not sure that is true. – jbchurchill Mar 28 '17 at 18:51

I would convert the data to decimal degrees first by opening the table into a spreadsheet program like Excel and adding a column and calculating ...

=LEFT(A2, 2) + (RIGHT(A2, FIND(" ", A2, 3)) / 60)

That will add two digit number before the space to the number after the space divided by 60 so the value "48 24.09" becomes "48.0015"

So to address Felix's comment, and more importantly, in the case that you have more than 2 digits in lat or long this next formula would work better since it uses the space.

=ABS(LEFT(A4, FIND(" ", A4, 3))) + (RIGHT(A4, FIND(" ", A4, 3)) / 60)
  • This will make -125 30 equal to -124.50 – FelixIP Mar 28 '17 at 19:15

Because of the space ArcMap will see it as a string field, and you can't do math on strings. DD = D + (m/60) + (S/3600), since you have decimal minutes it's just D + (M/60)

So in excel the value of Y2 should equal = W2 + (X2/60) then run the formula to the last record. Recalculate the Z field in the same fashion. Then copy each field and paste as Values, so the field contains numbers not a formula.

Once this is done, ArcMap should see these as choices in the Add X,Y Event field options. Don't forget to set the coordinate system, I believe this is 4326 (WGS-1984) Geographic.

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