New to Shape Files

[gene_denny]

I'm looking for some basic info on the use of a few shape files and am not able to find that magic post that explains it to me.  I've been using Alteryx for quite some time but primarily for blending, so I could really use some help.  My questions are two-fold.

I have the attached three files which show the boundaries for each of 5 high schools.  I want to be able to do two things with them if possible:

1.  Through Alteryx, layer these polygons over a map of the city of Des Moines, IA, and

2.  Export that map, with the polygons, into a file which could be then used by Tableau as, perhaps, and background map.

I've tried several of the spatial tools in Alteryx and I'm getting nowhere.  I gotta be honest, I don't even know where to start.  Anyone want to have a little fun and show me what's possible?

[CharlieS]

I can help with map creation anything else spatial, but I ran into issues rendering these objects in Alteryx.

I used a Poly-Split tool to break these spatial objects into points, then used a Spatial Info tool to break those points into Latitude/Longitude Values and got values like this:

CentroidX CentroidY
1621317   586189
1621313   586213
1621342   586278
1621379   586359

Do you know what projection system was used when you saved this file? When I input the shape file into Alteryx, it is unable to immediately render the objects because the default coordinate system is WGS84. If you know the other projection system (or have a custom one), the Alteryx Input tool has an option to configure that when you input the file. 

[gene_denny]

Thanks, Charlie.

I was wondering about needing a prj file as well, but like I said, I'm new to the spatial world in Alteryx.  I'm going to see what I can find out on the projection being used and will report back.  Would you be willing to attach the workflow that you DID create for this part of it?

[CharlieS]

I've never actually had to use a prj file before, so I'm excited to learn here too. I've attached the workflow I used to deconstruct the shape file into points and read the coordinate values of those points.

[Paulteryx]

Instead of doing it manually, you can go to the https://licenses.alteryx.com site and download the Tableau Starter Kit located under Starter Kits. It contains an example workflow called "Creating Polygons for Tableau. It's a simple process using a macro that will break down your polygons and make them ready for import to Tableau.

[gene_denny]

Thanks, Paul (love your handle, BTW)

I've had the toolkit in place for a long time and never even realized that was in there.  I use the Publish to Tableau Server on almost a daily basis, however.

So, I put the tool in place (see attached) which generates centroid points.  Bringing that through to Tableau, however, does not allow me to draw the polygon because the CentroidX and CentroidY fields are not in an understandable latitude and longitude format.  Is there a way to now convert that so that the polygons can be drawn on a Tableau map?  Or, better yet, can I now use that information within Alteryx to render a background map which contains those polygons either as a single layer or a separate layer?

I know these are probably annoying questions, but spatial work within Alteryx is absolutely foreign to me.

[Paulteryx]

No problem Gene,

I'm not familiar with the Tableau side of things, so I'm flying a little blind here. That said, spatial is one of my strong points. At the most basic level Latitude and Longitude are simply X,Y coordinates. Think of Latitude as CentroidY and Longitude as CentroidX. When inputting this to Tableau, does it ask for an X field and a Y field? If so, map them accordingly to Latitude and longitude and you should be good to go.

Cheers,

Paulteryx

[gene_denny]

That's what I've done, but I believe Tableau is looking for a format similar to:

Latitude (CentroidY):  41.5892

Longitude(CentroidX):  -93.6923

I don't know that I can convert the centroid field values in our example to this syntax.

[BenMoss]

I will take a look at this when I have a laptop, but something to note here is the tableau spatial macro suggested above is now out of date as Tableau can now work directly with shape files.

I would suggest you output a .shp file from your Alteryx workflow and then connect to this directly in Tableau.

That is assuming you are using a version of tableau at least 10.3 or newer.

Ben

[CharlieS]

@gene_denny What can you tell us about the source of these spatial objects? Did you or someone else create them? What software and version were they created in? I'm still trying to figure out a conversion for this  coordinate system, but I haven't had any luck yet.