Creating chainage points with distance from start point included
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04-10-2022 03:31 PM
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DuncanHornby
How much experience have you with writing python? The script behind the tool is located here:
c:\program files\arcgis\pro\Resources\ArcToolbox\scripts\generatepointsfromlines.py
Before you do anything I would strong suggest you make a copy of it as a back up in case you mess it up and destroy a system tool. You will need Admin privileges to overwrite this file.
Open the above script in your preferred IDE, spyder works well with ArcPro if you have installed it through ArcPro. I wrote a short blog here.
You need only replace the two functions in the code (create_feature_class and create_points_from_line) with the updated code below. Any lines I have added you will see a DDH comment to identify them.
def create_points_from_lines(input_fc, output_fc, spatial_ref, percent=False,
dist=True, add_end_points=False):
"""Convert line features to feature class of points
:param input_fc: Input line features
:param output_fc: Output point feature class
:param spatial_ref: The spatial reference of the input
:param percent: If creating points by percentage (or distance)
:param dist: The distance used to create points (if percentage == False).
The distance should be in units of the input (see convert_units)
:param add_end_points: If True, an extra point will be added from start
and end point of each line feature
:return: None
"""
if percent:
is_percentage = True
else:
is_percentage = False
create_feature_class(input_fc, output_fc, spatial_ref)
# Add a field to transfer FID from input
fid_name = 'ORIG_FID'
arcpy.AddField_management(output_fc, fid_name, 'LONG')
# Create new points based on input lines
in_fields = ['SHAPE@', 'OID@']
out_fields = ['SHAPE@', fid_name, "Distance"] # Add Distance field - Added by DDH on 12/4/22
with arcpy.da.SearchCursor(input_fc, in_fields) as search_cursor:
with arcpy.da.InsertCursor(output_fc, out_fields) as insert_cursor:
for row in search_cursor:
line = row[0]
if line: # if null geometry--skip
if line.type == 'polygon':
line = line.boundary()
if add_end_points:
insert_cursor.insertRow([line.firstPoint, row[1], 0]) # Added 0 - Added by DDH on 12/4/22
increment = (percent or dist)
cur_length = increment
if is_percentage:
max_position = 1.0
else:
max_position = line.length
while cur_length < max_position:
new_point = line.positionAlongLine(cur_length,is_percentage)
insert_cursor.insertRow([new_point, row[1], cur_length]) # Added cur_length - Added by DDH on 12/4/22
cur_length += increment
if add_end_points:
end_point = line.positionAlongLine(1, True)
if is_percentage:
insert_cursor.insertRow([end_point, row[1], 1]) # Added 1 - Added by DDH on 12/4/22
else:
insert_cursor.insertRow([end_point, row[1], line.length]) # Added length - Added by DDH on 12/4/22
try:
oid_name = get_OID_name(input_fc)
arcpy.JoinField_management(out_fc, fid_name, input_fc, oid_name)
except arcpy.ExecuteError:
# In unlikely event that JoinField fails, proceed regardless,
# as spatial and join field are already complete
pass
return
def create_feature_class(input_fc, output_fc, spatial_ref):
"""Create the initial feature class
:param input_fc: Input line features
:param output_fc: Output point feature class
:param spatial_ref: The spatial reference of the input
"""
desc = arcpy.Describe(input_fc)
# Take flag environment over Describe property unless set to default
support_m = arcpy.env.outputMFlag.upper() if arcpy.env.outputMFlag in ['Enabled', 'Disabled'] \
else "ENABLED" if desc.hasM else "DISABLED"
support_z = arcpy.env.outputZFlag.upper() if arcpy.env.outputZFlag in ['Enabled', 'Disabled'] \
else "ENABLED" if desc.hasZ else "DISABLED"
# Create output feature class
arcpy.CreateFeatureclass_management(
os.path.dirname(output_fc),
os.path.basename(output_fc),
geometry_type="POINT",
has_m=support_m,
has_z=support_z,
spatial_reference=spatial_ref)
# Add Distance field - Added by DDH on 12/4/22
arcpy.AddField_management(out_fc,"Distance","Double",None,None,None,"Distance along line",True,False,None)
return
An example of the output is below:
Ideally ESRI would add this functionality to their core release
