topic Re: Spatial Join help. in Python Questions

Spatial Join help.

CCWeedcontrol — Tue, 16 Aug 2016 22:37:07 GMT

When i do a spatial join from a FEMA layer and Taxparcels it get multiple Fema zones like 'AEXXXAEXAE', 'AEAEXAEAEXAEAEAEXAEXAEXAEX'. I use the following + """FEMA_ZONE "FEMA_ZONE" true false false 60 Text 0 0 ,Join,#,"""+ FEMA09 + """,FLD_ZONE,-1,-1;"""\. I know the tool is doing what it is suppose to be doing. There is multiple "X" and "AE" zones that overlap this parcel. For the most part there are hundreds like this. Is there a why for example to just put "AE,X" instead of "AEAEXAEAEXAEAEAEXAEXAEXAEX". The only thing i can think of is to write and update cursor for each different FEMA_ZONE, but that would alot of update Cursor's.

I would appreciate any help, thanks.

Re: Spatial Join help.

DanPatterson_Retired — Tue, 16 Aug 2016 22:54:31 GMT

does it return a string or a list?

are these all the conditions or are there others?

Are they all different lengths?

are they unique in their first letter? or do you have AE AD etc

are they always text or do some begin with or contain numbers?

Re: Spatial Join help.

CCWeedcontrol — Tue, 16 Aug 2016 23:01:25 GMT

Its a string

These are all the conditions

yes they have different lengths

In the FEMA Layer they are only 'A', 'AE', 'AH', 'AO' or 'X'

Just text ('A', 'AE', 'AH', 'AO' or 'X')

Thanks.

Re: Spatial Join help.

DanPatterson_Retired — Tue, 16 Aug 2016 23:17:44 GMT

and there is no separator in the result at all? like a space? I am just trying to figure out how they all got concatenated together in the first place

Re: Spatial Join help.

CCWeedcontrol — Wed, 17 Aug 2016 15:19:59 GMT

No there are not separators. In the attached picture the blue highlighted is the parcel and you can see that FEMA_ZONES 'X', 'AE', 'AE', 'AE', 'X', 'X' intersect the parcel so it's adding/joining all the FEMA_ZONES into one attribute 'AEXXXAEXAE' which i believe that's what it is suppose to do. i just need it to have AE/X or AE,X i don't need all the extra AE's and X's.

Re: Spatial Join help.

DanPatterson_Retired — Sat, 11 Dec 2021 12:08:08 GMT

The only case ruining a really simple solution is the single occurence of case 'A', but that can be overcome b y subtracting the result of the sum of all the cases that begin with 'A' from the other combinations. Here is a start

>>> combos = ['A', 'AE', 'AH', 'AO', 'X']
>>> case = "AAAEAHAHXAOAEAXAOAH"
>>> num = [[i, case.count(i)] for i in combos]
>>> num
[['A', 10], ['AE', 2], ['AH', 3], ['AO', 2], ['X', 2]]
‍‍‍‍‍

you will notice that there are 10 occurrences of 'A' but there are 2x 'AE', 3x 'AH' and 2 x 'AO for a total of 7 leaving 3 cases of pure 'A'

case = "A A AE AH AH X AO AE A X AO AH"

so it is correct.

So You can parse that into a def from the calculation should you wish to return one of each unique value, or the dominant (ie AH in this case) or whatever. I will leave that choice up to you, hope this gets you started

Re: Spatial Join help.

WesMiller — Wed, 17 Aug 2016 17:34:50 GMT

You could use Dissolve—Help | ArcGIS for Desktop on your fema dataset then use spatial join then you would only have one record for each type.

Re: Spatial Join help.

CCWeedcontrol — Wed, 17 Aug 2016 18:30:04 GMT

Dissolving the FEMA Layer seemed to reduce the number of them but completely give me the results i am after.

Thank you for the suggestions

Re: Spatial Join help.

CCWeedcontrol — Sat, 11 Dec 2021 12:08:10 GMT

I've been trying to do something like this but attributes don't seem to change.

with arcpy.da.UpdateCursor("In_memory\PT_Lyr", "FEMA_ZONE") as cursor:
            for row in cursor:
                if row[0] in ['AEX','AEXX']:
                    row[0] = 'AE/X'
                elif row[0] in ['AAEAEXX','AAEX','AAEAEX']:
                    row[0] = 'A/AE/X'
                elif row[0] in ['AAE','AAEAE']:
                    row[0] = 'A/AE'
                    cursor.updateRow(row) 
            del row‍‍‍‍‍‍‍‍‍‍

Re: Spatial Join help.

DanPatterson_Retired — Mon, 22 Aug 2016 19:29:24 GMT

cursor.updateRow(row) needs to be un-indedented (aka dedented) one level to line up with the last elif, otherwise, the update for previous conditions won't occur

Re: Spatial Join help.

CCWeedcontrol — Mon, 22 Aug 2016 20:24:24 GMT

Doh!

I looked into your suggest to parse that into a def but was not successful at all.

I appreciate the help.

Thanks.