topic Re: Structure area definition query in python in Python Questions

Structure area definition query in python

deleted-user-25j2k-XonNEg — Tue, 26 Mar 2019 21:19:53 GMT

I'm writing a Python script tool that will generate a map and am stumped on one item. The user enters the fire station number, the minimum area (in square feet) of structures to be displayed, and up to seven optional layers. The tool will then create a PDF of the map.

Everything else works fine but I keep getting an error on the structure size (SHAPE.AREA). The code for this particular part is:

sqft = arcpy.GetParameterAsText(2)
stru = m.listLayers('Structures')[0]
stru.definitionQuery = """{} >= {}""".format(arcpy.AddFieldDelimiters(stru, 'SHAPE.AREA'), sqft)

The tool parameter for sqft is set to Double. The script completes without crashing, however the structure layer does not display and I get an error if I try to open the attribute table: "Underlying DBMS error [ORA-00904: "SHAPE.AREA": invalid identifier]. Manually setting the definition query to SHAPE.AREA >= 5000 works fine, but I can't get it to go in Python. I'm using ArcGIS Pro 2.3.1; I have not tried building the map and tool with ArcMap.

Thanks in Advance,

Charlie

Re: Structure area definition query in python

PavanYadav — Tue, 26 Mar 2019 23:19:53 GMT

Can you see if the same works from the Python Window?

Re: Structure area definition query in python

deleted-user-25j2k-XonNEg — Wed, 27 Mar 2019 13:12:14 GMT

I get the same error using the Python Window. If I look at the definition query in the layer properties, it looks OK (SHAPE.AREA >= 10000).

If, I then edit the definition query (through layer properties, not Python) by selecting the drop-downs for the fields and relationship, then add 10000, it works fine. Likewise, this works in the Python Window. I may just have to hard code some preset area values using if statements for now.

stru.definitionQuery = 'SHAPE.AREA >= 10000'

Re: Structure area definition query in python

RichardFairhurst — Sun, 12 Dec 2021 08:07:10 GMT

You have quoted the string wrong. Just use one pair of double quotes, not 3 pairs.

Also, you may want to try using code to get the area field name instead of hard coding a name that only works for a specific database. something like the following should work

sqft = arcpy.GetParameterAsText(2)

stru = m.listLayers('Structures')[0]
fc = stru.dataSource
desc = arcpy.Describe(fc)
areafieldname = desc.areaFieldName
stru.definitionQuery = "{} >= {}".format(arcpy.AddFieldDelimiters(stru, areafieldname), sqft)‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍

Re: Structure area definition query in python

deleted-user-25j2k-XonNEg — Wed, 27 Mar 2019 15:07:13 GMT

Thanks.

I'll give it a shot, though Esri documentation shows three sets of double quotes, and that way works fine with setting the station's first-due area.

Charlie

Re: Structure area definition query in python

PavanYadav — Wed, 27 Mar 2019 16:12:37 GMT

Thanks for checking. The reason I asked because recently when I was using a definitionQuery from a python tool, ArcGIS Pro returned an error (or, did not do anything; don't recall exactly) but I used the same definitionQuery from the python window, it worked as expected. I did not do any additional tests at that time, but I felt it’s a problem in the software. I will do some more testing and let you know what I find out.

Re: Structure area definition query in python

DanPatterson_Retired — Sun, 12 Dec 2021 08:07:12 GMT

"{} >= {}".format('a', 10)
'a >= 10'

"""{} >= {}""".format('a', 10)
'a >= 10'

"""""""""{} >= {}""""""""".format('a', 10)
'a >= 10'‍‍‍‍‍‍‍‍

Left and right just need to match/balance in python

Re: Structure area definition query in python

RichardFairhurst — Wed, 27 Mar 2019 16:36:18 GMT

Good to know, but in several languages the use of multiple quotes together makes the quotation mark a literal character within a string and 3 pairs of quotation marks together would return a quoted string within a string equivalent to:

'"a >= 10"'‍‍‍‍

So given that your examples show that only the first pair of quotation marks is required in Python to get the desired output, I consider the use of more than one pair of quotations both unnecessary and potentially confusing to those familiar with other languages (as it was to me).

Re: Structure area definition query in python

DanPatterson_Retired — Sun, 12 Dec 2021 08:07:15 GMT

"""""""""'{} >= {}'""""""""".format('a', 10)
"'a >= 10'"‍‍

'''''''''"{} >= {}"'''''''''.format('a', 10)
'"a >= 10"'‍‍‍‍‍

which why a knowledge of balance and quote type is important

Re: Structure area definition query in python

deleted-user-25j2k-XonNEg — Wed, 27 Mar 2019 16:49:01 GMT

I thought that using the Describe function that Richard suggested would work, but it isn't displaying any structures. I'll go back to the hard-coded statements for now; there are only three choices at this point I'll further check it as a stand-alone script and see if that makes any difference and add more flow traces.

Thanks to everyone.

Charlie

Re: Structure area definition query in python

RichardFairhurst — Wed, 27 Mar 2019 16:54:55 GMT

After your code sets the definition query you should print it to verify that it is the string you expected:

print(stru.definitionQuery)‍

Re: Structure area definition query in python

deleted-user-25j2k-XonNEg — Wed, 27 Mar 2019 17:16:51 GMT

I do (though with arcpy.AddMessage).

I made a slight change as I don't like long variable names.

# Set structure area size filter.
stru = m.listLayers('Structures')[0]
fc = stru.dataSource
desc = arcpy.Describe(fc)
area = desc.areaFieldName
stru.definitionQuery = "{} >= {}".format(arcpy.AddFieldDelimiters(stru, area), sqft)
arcpy.AddMessage('Structure Filter: {}'.format(stru.definitionQuery)) ## Flow trace

I notice that the field's case changes from all caps to mixed (SHAPE.AREA vs Shape.AREA) but the results are the same. I may also try ArcMap and Python 2.x to see what happens. I have a couple more tweaks to do like getting the scale bars properly set, so this is not a major problem. Hard coding will work for the time being.

Re: Structure area definition query in python

RhettZufelt — Thu, 28 Mar 2019 19:23:28 GMT

Not sure where your data resides, but I have noticed with 10.2.1 arcmap and SDE data on SQL Server, the desc.areaFieldName reports u'Shape.area' even though in Catalog/Map it says it is 'Shape.STArea()'.

If I try to use the value returned from Describe, it does not select anything. If I use the Shape.STArea(), everything works fine.

Re: Structure area definition query in python

deleted-user-25j2k-XonNEg — Mon, 01 Apr 2019 21:22:25 GMT

I found one issue - I'm using GetParametersAsText, so a string is being passed along. I will try GetParametes to get the integer. I will post if I figure it out.

Re: Structure area definition query in python

DanPatterson_Retired — Mon, 01 Apr 2019 23:00:09 GMT

you could just int(arcpy.GetParameterAsText(2))