topic Re: merging two features from the same shapefile in Python Questions

merging two features from the same shapefile

BryceGardner1 — Fri, 22 Nov 2013 11:37:35 GMT

I have a shapefile with all the roads in my county. Unfortunately, they are in segments. I am trying to combine them all into the same shapefile where each road has one continuous segment instead of hundreds of little segments.

I thought about using a loop, SearchCursor, selectByAttribute, and unSplitLine, but that is going to put them all into separate shapefiles (or continuously overwrite them). I need them all in the same shapefile so I can run my analysis on them.

Any thoughts about how I can move forward are appreciated.

Thanks,

Bryce

Re: merging two features from the same shapefile

XanderBakker — Fri, 22 Nov 2013 12:06:25 GMT

Hi Bryce,

Did you try the "Dissolve (Data Management)" tool? Dissolve on your Road ID or name field and with these options:

Create multi part features (switched off)

Unsplit lines (switched on)

There is also the "Unsplit Line (Data Management)" tool (Advanced license).

Kind regards,

Xander

Re: merging two features from the same shapefile

BryceGardner1 — Fri, 22 Nov 2013 12:08:18 GMT

Thanks for your reply, Xander. I will try that.

Thank You,

Bryce

Re: merging two features from the same shapefile

BryceGardner1 — Fri, 22 Nov 2013 12:45:58 GMT

The dissolve tool is working almost as well as it should. For example, the original shapefile has 24 records for E MARKET ST. The dissolved shapefile has 5 records for it. I tried changing to DISSOLVE_LINES thinking that maybe the end vertices aren't exactly coincident, but I am still getting the same result. Any thoughts?

Re: merging two features from the same shapefile

XanderBakker — Fri, 22 Nov 2013 12:55:16 GMT

Hi Bryce,

I would probably start with trying to find out why those features couldn't be dissolved into one feature. If they exactly connect, then maybe the direction of the lines is not matching? Try and symbolize the lines using a Cartographic Line Symbol, with in the Line Properties tab defining a line decoration as an arrow (second of the three options). What do you see?

Another possibility is going into edit mode and examine the feature vertices. Select a feature click Edit Vertices and look at the sketch properties. In case of Z or M do they match?

If you want share a few features and I can have a look at it...

Kind regards,

Xander

Re: merging two features from the same shapefile

BryceGardner1 — Fri, 22 Nov 2013 13:13:39 GMT

Yes, that appears to be the problem. The lines are pointing in opposite directions for whatever reason. Is there a way around this? I would share the features with you if I knew how. I tried attaching a shapefile, but it seems that is unsupported by the attachment manager.

Re: merging two features from the same shapefile

XanderBakker — Fri, 22 Nov 2013 13:31:45 GMT

You can ZIP the files of the shapefile and attach the zip.

It should be possible to flip the lines. I'll look into it.

Re: merging two features from the same shapefile

BryceGardner1 — Fri, 22 Nov 2013 13:50:08 GMT

I am learning more than I bargained for here. :cool: Here is the zip file.

Re: merging two features from the same shapefile

BryceGardner1 — Fri, 22 Nov 2013 13:59:44 GMT

I just tried using switching to MULTI-PART instead of SINGLE_PART. It worked! It doesn't matter if they are separated, the street names in our county aren't allowed to clash with one another. So, we only have one road name per road, instead of a weird situation where 11th St. is on two different sides of town. Thank you for all your help, Xander.

Re: merging two features from the same shapefile

BryceGardner1 — Fri, 22 Nov 2013 14:01:09 GMT

Now, where is the green checkmark? I want to show others that this was answered.

Re: merging two features from the same shapefile

XanderBakker — Fri, 22 Nov 2013 14:07:17 GMT

I just tried using switching to MULTI-PART instead of SINGLE_PART. It worked! It doesn't matter if they are separated, the street names in our county aren't allowed to clash with one another. So, we only have one road name per road, instead of a weird situation where 11th St. is on two different sides of town. Thank you for all your help, Xander.

Hu Bryce,

Glad to hear that the multiparts work for you. In case you want to eventually correct the lines, there is a tool called "Flip Line (Editing)", which can flip the orientation of a polyline. (It is available for standard and advanced licenses.)

In ArcObjects the IPolyline interface has a ReverseOrientation method. I don't see this in arcpy, but it wouldn't be too difficult to write.

Kind regards,

Xander