I have a function that comes really close to this. Instead of attributing with the count, it attributes with a unique "neighborhood" ID. It could easily be modified to report the count instead. Or, you could run this first and then get the counts with a simple cursor and a dictionary.
To directly attribute with counts, replace all instances of
row[0] = id_out
with:
row[0] = count_post
Also, the function below has a few additional parameters to fine-tune your groupings of features, but they may be superfluous for your needs.
I edited it to remove some dependencies, and I haven't tested the edits, but it should be really close.
import os
import datetime
import arcpy
def assign_neighborhood_id(feature_class, neighborhood_field, dissolve_fields=None, search_distance='0 FEET', where_clause=None):
"""
(str, [str], [collection], [str]) -> str
To each disjunct cluster of features, assign a unique neighborhood ID.
Parameters:
feature_class - The path/name of the feature to which you wish to assign
neighborhood IDs
neighborhood_field - The name of the field to which the IDs will be
assigned.
dissolve_fields - A field name or a collection of field names within which
features must have identical values in order to be considered neighbors.
search_distance - By default, neighbors will be identified by an
intersection, however, if you wish to allow for gaps between features,
you may enter an ArcGIS-compatible search distance here. By default or
if None is passed, then '0 FEET' will be used.
where_clause - Only features satisfying the where clause will be considered
part of a neighborhood; all other features will have a Null value in the
neighborhood field.
"""
if not search_distance:
search_distance = '0 FEET'
if neighborhood_field not in [i.name for i in arcpy.ListFields(feature_class)]:
arcpy.AddField_management(feature_class, neighborhood_field, 'LONG')
already_layer = arcpy.Describe(feature_class).dataType == 'FeatureLayer'
if (already_layer and where_clause) or not already_layer:
# Ensure a unique, unused name for the in-memory layer
lyr = os.path.join('in_memory', 'f{}'.format(datetime.datetime.now().strftime('%Y%m%d%H%M%S%f')))
arcpy.MakeFeatureLayer_management(feature_class, lyr, where_clause)
else:
lyr = feature_class
fn_oid = arcpy.Describe(feature_class).OIDFieldName
vs_oid = set([row[0] for row in arcpy.da.SearchCursor(lyr, fn_oid)])
select_type = 'INTERSECT'
id_out = int()
# If there are fields on which to dissolve
if dissolve_fields:
# Get a list of the names of string/date fields
fns_string = [i.name for i in arcpy.ListFields(lyr) if i.type in ('String', 'Date')]
# Compile a list of where clauses, one for each field
wcs_components = list()
for index, field in enumerate(dissolve_fields):
if field in fns_string:
wc_base = "{} = '{}'"
else:
wc_base = '{} = {}'
wcs_components.append(wc_base.format(field, '{}'))
# Compile the full where clause, but without values
wc_diss = ' AND '.join(wcs_components)
for v_oid in vs_oid:
wc_seed = '{} = {}'.format(fn_oid, v_oid)
# If the feature is already assigned to a neighborhood, skip it.
if [x[0] for x in arcpy.da.SearchCursor(lyr, neighborhood_field, wc_seed)][0] is not None:
continue
# Create the where clause for querying suitable neighbors
with arcpy.da.SearchCursor(lyr, dissolve_fields, wc_seed) as cur:
for row in cur:
vs_seed = row
break
if None in vs_seed:
wcs_components_null = list()
for index, v in enumerate(vs_seed):
if v is None:
wcs_components_null.append('{} IS NULL'.format(dissolve_fields[index]))
else:
wcs_components_null.append(wcs_components[index].format(v))
wc_diss_use = ' AND '.join(wcs_components_null)
else:
wc_diss_use = wc_diss.format(*vs_seed)
# Run the initial selection
arcpy.SelectLayerByAttribute_management(lyr, None, wc_seed)
count_initial = 1
arcpy.SelectLayerByLocation_management(lyr, select_type, lyr, search_distance)
arcpy.SelectLayerByAttribute_management(lyr, 'SUBSET_SELECTION', wc_diss_use)
count_post = len(arcpy.Describe(lyr).FIDSet.split(';'))
while count_initial < count_post:
# Update the initial count
count_initial = count_post
# Select intersecting
arcpy.SelectLayerByLocation_management(lyr, select_type, lyr, search_distance)
# Remove those that don't match the attributes
arcpy.SelectLayerByAttribute_management(lyr, 'SUBSET_SELECTION', wc_diss_use)
# Update the current select count and the iterations count
count_post = len(arcpy.Describe(lyr).FIDSet.split(';'))
# Assign the IDs
with arcpy.da.UpdateCursor(lyr, neighborhood_field) as cur:
for row in cur:
row[0] = id_out
cur.updateRow(row)
arcpy.SelectLayerByAttribute_management(lyr, 'CLEAR_SELECTION')
# Increment the ID
id_out += 1
# If no dissolve fields are required
else:
for v_oid in vs_oid:
wc_seed = '{} = {}'.format(fn_oid, v_oid)
# If the feature is already assigned to a neighborhood, skip it.
if [x[0] for x in arcpy.da.SearchCursor(lyr, neighborhood_field, wc_seed)][0] is not None:
continue
# Run the initial selection
arcpy.SelectLayerByAttribute_management(lyr, None, wc_seed)
count_initial = 1
arcpy.SelectLayerByLocation_management(lyr, select_type, lyr, search_distance)
count_post = len(arcpy.Describe(lyr).FIDSet.split(';'))
while count_initial < count_post:
# Update the initial count
count_initial = count_post
# Select intersecting
arcpy.SelectLayerByLocation_management(lyr, select_type, lyr, search_distance)
# Update the current select count and the iterations count
count_post = len(arcpy.Describe(lyr).FIDSet.split(';'))
# Assign the IDs and increment the ID
with arcpy.da.UpdateCursor(lyr, neighborhood_field) as cur:
for row in cur:
row[0] = id_out
cur.updateRow(row)
arcpy.SelectLayerByAttribute_management(lyr, 'CLEAR_SELECTION')
id_out += 1
return neighborhood_field
