topic Re: adding X-Y data from a table in Data Management Questions

adding X-Y data from a table

RGCOG_Rural — Thu, 14 Jan 2016 22:00:11 GMT

When I add X-Y data from a spreadsheet into 10.2.2, the points do not plot correctly. I followed the steps in the knowledge base article (27589), and have tried projecting, reprojecting, using an existing layer as the coordinate system, changing from one coordinate system to another and back, and starting with a blank map - which plots the points correctly, but sends anything I add to another location. I am using NAD 83 State Plane 4203. The area where the points should plot is around 30 N, -103 W, but they plot at 3N, -105 W.

I converted the coordinates to numbers to 8 decimal places. I tried with both csv and xlsx spreadsheets. Anyone have any ideas?

Re: adding X-Y data from a table

ChadKopplin — Thu, 14 Jan 2016 22:05:14 GMT

can you show one of your x and y coordinates? I suspect that the wrong coordinate system is being used for the records versus what you need the coordinates to be in.

Re: adding X-Y data from a table

DanPatterson_Retired — Thu, 14 Jan 2016 22:10:33 GMT

the only things in common between the two systems you referred to...NAD83 is a datum and not a coordinate system. I suspect your data is one coordinate system or the other, but changing to 8 decimal places means it is probably not the state plane, since it is a projected coordinate system and 8 decimal places is approximating nanometer precision. So perhaps it is in decimal degrees, so examine the extents in the layer's properties

Re: adding X-Y data from a table

RGCOG_Rural — Thu, 14 Jan 2016 22:19:34 GMT

I’ve attached part of the table, without the columns that contain identifying data.

Thanks!

Catherine

Catherine Crumpton

911 GIS Coordinator

Rio Grande Council of Governments

432-837-7199

500 W Ave H, Room 115, Box 3

Alpine TX 79830

Re: adding X-Y data from a table

RGCOG_Rural — Thu, 14 Jan 2016 22:29:18 GMT

I do use decimal degrees and I use a projected coordinate system. So perhaps I should remove some of decimal places and try again. I was following the steps in the KB article when I added them.

Thanks!

Re: adding X-Y data from a table

DanPatterson_Retired — Thu, 14 Jan 2016 22:29:19 GMT

you have decimal degree data that was downloaded to 6 decimal places, changing it to 8 will not improve things. So you are at 30 degrees latitude ish define it as a geographic coordinate system NAD83 ( aka

GCS NAD83

Re: adding X-Y data from a table

DanPatterson_Retired — Thu, 14 Jan 2016 22:30:46 GMT

ps add the data to a new empty data frame devoid of other data when you define its projection, so that things don't get muddled from other data

Re: adding X-Y data from a table

RGCOG_Rural — Thu, 14 Jan 2016 22:36:28 GMT

I tried that, and when I added other layers they no longer were in the correct location. These were points in a city, and when I added the city limits polygon, it was way down west of Colombia

Re: adding X-Y data from a table

DanPatterson_Retired — Thu, 14 Jan 2016 22:42:16 GMT

by any chance, latitude is the Y coordinate and longitude is the X coordinate,

add that data, check its extents in properties. if the latitude and longitude look correct in the spreadsheet, then they are correct...don't assume the other data are.

Re: adding X-Y data from a table

RGCOG_Rural — Thu, 14 Jan 2016 22:46:28 GMT

I am adding the x-y data to a new map. Does it make a difference whether I define the coordinates system in the Add XY Data dialogue box or not? As I understand it, the map will use the first layer added as the coordinate system, so maybe I need to add it and then use data frame properties to define it?

Re: adding X-Y data from a table

DanPatterson_Retired — Thu, 14 Jan 2016 22:50:39 GMT

add it without defining anything is my preference... you dataframe if empty, will be undefined... that is fine.
save the event layer to a shapefile or a featureclass in an empty geodatabase.
Use the Define Projection tool in the data management, projections and transformations toolset
at this stage you haven't tainted anything because you have placed it all by itself .

Once you have defined the coordinate system, you may let the others in to play and hope they play nice

Re: adding X-Y data from a table

DarrenWiens2 — Thu, 14 Jan 2016 22:56:28 GMT

This works for me:

1.) Add your Excel to ArcMap

2.) Display XY Data...

3.) X Field = Longitude, Y Field = Latitude, Coordinate System = GCS_WGS_1984 (or NAD83 if you prefer)

That is it. It does not matter one iota whether your data frame is defined beforehand or not.

Re: adding X-Y data from a table

RGCOG_Rural — Thu, 14 Jan 2016 22:57:28 GMT

Works great, but when I add another layer, the added layer is out in the ocean, even though the propertis show the same coordinate system. Thanks for all your help - will try again tomorrow!

Re: adding X-Y data from a table

DanPatterson_Retired — Thu, 14 Jan 2016 23:00:15 GMT

it is recommended to remove any queries about dataframe coordinate systems... If it is empty and undefined, you have a clean slate, without other influences

Re: adding X-Y data from a table

DarrenWiens2 — Thu, 14 Jan 2016 23:07:35 GMT

Since you're defining the event layer CRS in the Display XY dialog, the data frame has no bearing on the matter, but be my guest and start fresh. This topic was just getting lost in irrelevant details.

Re: adding X-Y data from a table

DanPatterson_Retired — Thu, 14 Jan 2016 23:27:11 GMT

well it was just between the two of us, and I wanted to remove any potential places of confusion that I have seen in the past... but that has been what has worked for me and it has headed off the many times that I have seen students define the coordinate system while they were making the event layer, thenm used the define projection tool to try to "make" it projected. If the define projection can only be made once, then you are further ahead. It has worked for me... short cuts come later

Re: adding X-Y data from a table

NeilAyres — Fri, 15 Jan 2016 07:11:46 GMT

Dan Patterson wrote:
add it without defining anything is my preference... you dataframe if empty, will be undefined... that is fine.
save the event layer to a shapefile or a featureclass in an empty geodatabase.
Use the Define Projection tool in the data management, projections and transformations toolset
at this stage you haven't tainted anything because you have placed it all by itself .
Once you have defined the coordinate system, you may let the others in to play and hope they play nice

Sorry Dan, but here I don't agree.

When creating a XY event layer, it is important that you know what the imported coordinates actually are.

And then, as Darren says, it doesn't matter what the df crs actually is.

But we get many, many queries here re the exact same problem.

Re: adding X-Y data from a table

DanPatterson_Retired — Fri, 15 Jan 2016 07:22:03 GMT

I didn't say that you didn't need to know what they are...I said when you should define them. As indicated...I find defining them as a separate step removes the glitch that I have seen countless times, when they define the coordinate system when the data are added in the XY step, then get confused and use the define projection tool instead of the project tool.

So my suggestion, is .... 1 dump it into an empty data frame undefined using the add xy tool... 2 then use the define projection tool to define it... 3 then project it to what they want (if any). When done, drag it off to the dataframe with all the other data and hopefully everything plays nice. Now obviously you can combine steps 1 and 2 and the interminably clever would see that but ... I have seen every combination and permutation of what can go wrong when people don't think "big picture" but are linear thinkers. You have seen the muddle that arises on the forums yourself over the years.

Re: adding X-Y data from a table

NeilAyres — Fri, 15 Jan 2016 07:34:38 GMT

I have been doing GIS stuff for ~ 30 years now.

And, yes, these days the software is much easier to use and the hardware is much faster.

But, even today, just about every project I have had a hand in, the main problems are data & people.

The people problem is knowledge, training and awareness. Plus all those nasty corporate issues.

And data is data.

If someone tells me that their "data is perfect", I know that they are lying.

And you only find out about the data when you go and look at it.....