Latest Contributions by DavidMedeiros

I'm assuming you are joining your xls layer to the points feature class (not the other way around). You could create dummy empty fields before the join (with same data types as the xls table fields) and then after the join, populate those fields based on the joined table fields. That way, the data will remain permanently in the points feature class, even after the join is removed. Joining table to points, then using Data>Export Data... to make a permanent copy of the points layer. I've done this hundreds of times and is basically the primary method for making a join permanent in ArcGIS. I've encountered the empty export issue a few times here and there but not the problem I described 2) above. Either way this is generally a straightforward function that we use all the time in Arc. It may be here data that's causing the problem, but I can't think of why. ... View more

A couple approaches come to mind:  the Near command, described here or perform a buffer around each earmark point and then geoprocess the buffers into/with the districts. I'm purposely leaving this a little vague as I'd like your student to figure out the specifics.... Thanks. We usually just help with general understanding of the software and science itself but with no actual GIS curriculum on campus we often have to delve into holding hands through analysis design as well. I'd considered buffers but there may be cases where a buffer would cross into nearby districts that don't actually belong to the city the earmark is in. Dialing in the exact right tolerance for a few thousand entrie3s across all 50 states would be difficult if not impossible. I may have come up with a solution though. I'm intersecting the ESRI placeply layer with the congressional districts to get a layer of polygons that contain both the district id and the city it falls into (or more specifically, pieces of the districts broken into their city portions). Table join the earmarks to the intersected layer by city/sate name then merge the output back into districts only on the district name. Still need to figure out the count and proportional sum issue but I think this moving in the right direction. Still looking for input though. ... View more

Strange.. I just tried to make the iterators connect to the ascii 3d tool, no problem, immediately connected as input. I don't know what would be wrong, have you updated to the latest SP? Interesting. What's the ASCII 3d tool? Is that the exact same tool as "ASCII to Raster"? I'll check our SP version when I'm in next (not until Tuesday). Thanks for checking. ... View more

What i see right away is the raster iterator. have you tried using the Iterate files instead? it reads files in a folder and can push that file to a tool, such as the ascii to raster tool Tried all of the iterators, none will link as an input. The "Iterate Files" specifically only has the option to set itself as the precondition to the ASCII tool. ... View more

I think Featue To Line tool (ArcInfo license) breaks lines where they intersect or share a segment. Each output line carries the FIDs of all the sharing lines, or -1 for no sharing line with an input fc. You would need to add a field to the result and calculate the count of FIDs that are not -1 by an expression. Again, thank you. That worked as well. I never look to these tools as geometry tools but should probably know more about them (meaning the "feature to..." tools). I did have to massage the table after words. There may be a more automated way of doing this but I simply used a series of selections and field calculations to change the values in each of my 6 FID fields to either a 1 or 0 then used the field calc to sum those into a new column. Now looking at how to create an accumulation of values for each segment based on its location in the river network and the values of all downstream segments. This is going to be a lot more involved and complex so I'll just post a new topic. ... View more

Thank you for letting me know. You are welcome. I am glad it worked for you.  🙂 I have a new similar question if you're interested? I have 6 line feature classes, each one is of a particular fish species distribution in the Oregon river system. Each feature class contains only the line features where that species is present, some lines overlap between the 6 layers, some don't. I want to output a new layer that is a collection of all the river segments from the 6 layers where each segment contains the count of the species in that segment and the unique species names. Union (Analysis) looks like it does what I want but this is a polygon only tool. I think I could do this thru a series of spatial joins to a master hydrology layer but a one time merging of the 6 line layers would work better. Any ideas how I could best tackle this analysis? ... View more

When you run Spatial Join, you can specify a Merge Rule - Count on a field. In your case, for each line you can get a count of matched dam features (FIDs). Sorry for the late reply, thank you Dan, yes this worked great. ... View more

Well it turns out I have two variations on this problem that need to be addressed; one involves getting single overlap polygons that inherit the unique species ID from the input polygons (as already described above). The other version is to get overlap polygons that sum the values of one field from the input polygons, and I think I managed to do this today. Here's the work flow: add original polygon layer [union] polygons, keeping all attributes (stacks identical polygons) open table to union layer add 3 new fields; x_coord, y_coord & xy_id calculate geometry for x & y coord fields create UID by concatenating coordinates into the xy_id field [dissolve] union layer on xy_id; use a sum statistic operation during dissolve to sum selected values of stacked polygons (in this case the "count" field) output layer polygons are single non stacked polygons of the overlap and non overlap areas with a count sum from all identical polygons in its stack Does that seem right? It worked on my very basic sample file. For the other issue, retaining unique species info and concatenating into one field for the dissolved stack I found the link below. Will try later, not sure how complex the species data is (still have not interviewed the student). http://forums.arcgis.com/threads/12637-Union-intersect-Concatenate ... View more

The dissolve will need to be run so that you are left with a single polygon for each overlap, not stacked polygons. This is only possible if a UID has been generated for the overlapping polygons. One way to do this, is to generate a pt from the Unioned overlay, and dissolve those points based on their X,Y coordinates (matching UIDs in this case) and then create a new field and populate a UID using any method you are familiar with. in field calculator: "ABC" & "-" & [FID] + 1 or whatever Then perform a spatial join to transfer attributes from the centroid pt, to the unioned polygon. Your GDB should then be ready for the relate. That archived post does leave out a lot of intermediate steps because the assumption is that the user has some basic working knowledge of ArcGIS as seen in the initial post. Its assumed you know how to eliminate the stacked polygons (identical spatially) into a single polygon. And also how to populate a field to concatenate the values in the related table. In the last post of the archived forum, download the Zipped mxd and gdb to explore how it was done (hint: explore the GDB when in ArcCatalog to observe the relates, tables, structure, etc...) Ok, that work flow is making some sense to me now. Thank you. Work copy of Arc does not have the full Data Management tool box installed so can't generate points from poly here. But will give the process a try at the Library tomorrow. ... View more

How do you merge 2 identical polygons and combine / concatenate attributes use a relate after a dissolve (before dissolve, attribute table is exported for the relate later). I may not be understanding the example clearly but the Dissolve aggregates my separate polygons (if done after a Union) or simply does nothing when applied to my initial sample file and run on the Species field. Seems like such a simple action, to merge identical stacked polygons, or at least concatenate the species data into the top polygon in the stack. One key piece of info I am still missing (until I interview the student myself) is the exact need for this data. I'm assuming a simple need to visualize the overlap extents. ... View more