Dissolving feature/field by interval using ArcGIS Desktop?

I have a huge dataset with flowpaths containing a catchment area for each line. The attribute table has ~ 780.000 rows, and thereby 780.000 features in the mapwindow.

Is it possible by using a field to merge the data in intervals, so you get a multi-part feature instead?

For instance merge all the features so those with a catchment area of 1-10.000 become one, from 10.001-20.000, 20.001-30000 and so on? The interval doesn't have to be 10.000 but can be another value.

I was messing around with the dissolve feature, but other than doing a manual population of a field and then dissolving by that attribute, I couldn't find another way to do it.

Basically I want what the symbology window does, but I want to do it to the dataset.

I have ArcGIS Desktop 10.5.1 with the Advanced License.

Edit:

import pandas as pd
import arcpy

fc = r'C:UsersJGJDesktopDatabaseVejle.gdbStromningsVeje' #Change to match your data
bins = [-1,10000,50000,100000,200000,500000,1000000,5000000,10000000,100000000,1000000000] #Add/remove bins

df = pd.DataFrame.from_records(data=arcpy.da.SearchCursor(fc,['OID@','flow']),columns=['OID','flow'])
df['Interval'] = pd.cut(df['flow'], bins=bins).astype(str)

intervaldictionary = dict(zip(df.OID,df.Interval))

with arcpy.da.UpdateCursor(fc,['OID@','Intervalfield']) as cursor:
for row in cursor:
if row[0] in intervaldictionary:
row[1] = intervaldictionary[row[0]]
else:
row[1] = 'Unknown interval'
cursor.updateRow(row)


Ran into a snack, when processing a large dataset:

Runtime error
Traceback (most recent call last):
File "<string>", line 7, in <module>
File "C:Python27ArcGIS10.5libsite-packagespandascoreframe.py", line 950, in from_records
values += data
MemoryError


Any suggestions on how to get passed this?

1 Answer
1

Create a new field of intervals and assign an interval to each record. Then dissolve by interval field. This can be done with field calculator and many if-elif-elses or you can use pandas module (which is included in ArcGIS 10.5) and pandas.cut:

Use cut when you need to segment and sort data values into bins

Add a text field named Intervalfield, modify indicated lines and execute code in the python window of ArcMap. Then Dissolve by Intervalfield. If you want to use some other areafield instead of shapearea, replace SHAPE@AREA with the name of your field:

SHAPE@AREA

import pandas as pd
import arcpy

fc = r'C:data.gdbfeatureclass' #Change to match your data
bins = [-1,10,20,30,40,50,9999] #Add/remove bins

df = pd.DataFrame.from_records(data=arcpy.da.SearchCursor(fc,['OID@','SHAPE@AREA']),columns=['OID','Area'])
df['Interval'] = pd.cut(df['Area'], bins=bins).astype(str)

intervaldictionary = dict(zip(df.OID,df.Interval))

with arcpy.da.UpdateCursor(fc,['OID@','Intervalfield']) as cursor:
for row in cursor:
if row[0] in intervaldictionary:
row[1] = intervaldictionary[row[0]]
else:
row[1] = 'Unknown interval'
cursor.updateRow(row)


After code you will have output below, then dissolve.

If you get memoryerror you are out of ram. Then skip the pandas part and use the da.UpdateCursor with if-elif-else:

import arcpy

fc = r'C:data.gdbfeatureclass' #Change to match your data
areafield = 'SHAPE@AREA'
intervalfield = 'Interval'

with arcpy.da.UpdateCursor(fc,[areafield,intervalfield]) as cursor:
for row in cursor:
if row[0]<10000:
row[1] = '1' #Or '0-10000', whatever you want
elif row[0]<50000:
row[1] = '2'
#More elifs...
else:
row[1] = '9999'
cursor.updateRow(row)


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