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I did "Calculate Geometry" on a line shapefile to obtain the coordinates X and Y for the start and the end of all the lines of the shape. But some lines resulted with the same X on the start and on the end, and the same Y on the start and on the end.

If the line is crossed by other line, the X and Y that results is the X and Y of the point where the line is crossed. So X,Y are the same because it's a point. My question now is why Calculate Geometry does that?

This is one of the affected lines: enter image description here

Thsi is another line and its properties Sketch properties of one of the lines with problem

  • That's pretty simple actually, assuming your question is worded as intended. A line with the same X coordinate for both start and end is simply a vertical (longitudinal in GCS) line. One with the same Y coordinate is a horizontal (a latitude or parallel in GCS). If both are the same, per @DanC's answer then the line starts and ends at the same point (which may or may not be incorrect). Note that calc geometry lets you do start, end, and mid points on lines. It's not clear from your question exactly how you're doing things. – Chris W Apr 15 '15 at 20:36
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    Can you share a screenshot of some of the affected lines, as well as the calculation results in the attribute table? – nmpeterson Apr 15 '15 at 21:41
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    I've posted a screenshot of one of the affected lines – AndM Apr 16 '15 at 14:08
  • How many vertices does that line have (you can find this by double-clicking it during an edit session and checking the Sketch Properties window)? If it had for example three, a start, out to a point, then doubled back to its origin, I can see that result. I can also see things getting weird if it is a multi-part feature. Would it be possible to post the shapefile or an export of some of the problem records anywhere? Have you run check geometery on the file to verify everything is valid? – Chris W Apr 16 '15 at 23:32
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    That would require some vertex editing. Right now the reason it is multipart is you have two separate line segments represented as a single feature. You'd have to explode the feature and add a segment between wherever the two are disconnected, either as a new line or just adding another vertex to one with continue line, then merge it all back together. Or possibly delete one of the parts if it's just directly overlapping the larger part. – Chris W Apr 24 '15 at 18:07
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Did you take a look at any those lines to see what might be going on? Their start and end points may actually be in the same place, if they were drawn incorrectly. Select one of them and zoom to it. If it shows up as a point, that's why the XY coordinates of the start and end points are the same.

Depending on the coordinate system you're using, it's also possible that a very short line may appear to have the same start and end points because you just aren't seeing enough digits after the decimal point in your coordinates to see the difference.

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  • I selected some of the lines that have this problem and they are actually lines, not points. – AndM Apr 15 '15 at 15:26
  • I saw that if the line is crossed by other line, the X and Y that results is the X and Y of the point where the line is crossed. So I think that is the problem, but I don't know why it happens – AndM Apr 15 '15 at 15:27
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You can use the Feature Vertices to Points tool with BOTH_ENDs option checked, on your lines, that will give you start/end points of the lines. Then Add XY Coordinates to populate the resultant points with Lat / Long values.

Another way to go about your workflow.

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