The Create Random Points (Data Management) tool is available with an Advanced license or on a Basic or Standard license if you have 3D Analyst or Spatial Analyst. In this post we will look at creating the tool for use with a Basic license. We’ll keep it simple for now and just generate the desired amount of points per feature. Check out the Esri documentation for the Create Random Points tool.
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The syntax for the Create Random Points (Data Management) tool is as follows…
arcpy.management.CreateRandomPoints(out_path, out_name, {constraining_feature_class}, {constraining_extent}, {number_of_points_or_field}, {minimum_allowed_distance}, {create_multipoint_output}, {multipoint_size})
We’re going to take a different direction from the Create Random Points syntax and use three required parameters; in_features, the features you wish to generate random points for, these can be Point, Polyline, or Polygon; out_feature_class, the output Point feature class to create containing the random points; and number_of_points, the number of points to generate for each feature from the in_features.
Let’s get started by importing the necessary modules…
import arcpy
import random
…and then the required user inputs as discussed above.
## the input features to generate random points for
in_features = arcpy.GetParameterAsText(0)
## the output point feature class
out_feature_class = arcpy.GetParameterAsText(1)
## the number of points to generate for each feature
number_of_points = arcpy.GetParameterAsText(2)
We require four objects to help us with our workflow; the shape type of the in_features, whether it is Point, Polyline, or Polygon; the Spatial Reference System code so we can add as the SRS to the out_feature_class; the OID field from the in_features so we can assign to the ORIG_FID in the out_feature_class; and then to make sure that we cast the number of points from the input to an integer.
## shape type of in features - Point, Polygon, Polyline
shape_type = arcpy.Describe(in_features).shapeType
## srs id of the in_features so we can assign the output the same
srs_id = arcpy.Describe(in_features).spatialReference.factoryCode
## the OID field name from the in_features
oid_fld = [fld.name for fld in arcpy.ListFields(in_features) if fld.type=="OID"][0]
## make sure the number of points is an integer
number_of_points = int(number_of_points)
The memory workspace is fantastic for holding intermediate data in the workflow so we will use it to store or random generated points. We create a feature class in the memory workspace and then add an ORIG_FID field.
## a memory workspace feature class to store the random points generated
temp_fc = arcpy.management.CreateFeatureclass("memory", "temp_fc", "POINT", spatial_reference=srs_id)
## add ORIG_FID field to teh feature class
arcpy.management.AddField(temp_fc, "ORIG_FID", "LONG")
Now for the magic to happen! We need to account for our three possible shape types; Point, Polyline, and Polygon.
If the in_features are Points, we need to know if the number_of _points entered is greater than or equal to the number of records in the in_features. If the number_of_points is indeed greater or equal to the record count, then all points are exported as ‘random points’. However, if the number_of_points is less than the record count of the in_features, then we generate a random selection of OID values and use an Insert Cursor with a where clause to add the points to our memory feature class.
If the in_features are Polylines, we combine the use of an Insert Cursor with our memory feature class with a Search Cursor for our in_features and use a random distance along each line to generate each random point.
Finally, if the in_features are Polygons, we combine the use of an Insert Cursor with our memory feature class with a Search Cursor for our in_features, we get the minimum bounding extent for each Polygon features and generate random X and Y coordinate pairs the fall within the bounding extent. We perform a test that the random point is contained by the polygon geometry and if not, go again until it is.
## if the in_features are Points
if shape_type == "Point":
num_points = int(arcpy.management.GetCount(in_features)[0])
## if the number of random points required is more than the points in in_features
if number_of_points >= num_points:
## no need for a where clause if the number of points from user input
## matches or exceeds the number of points in the in_features
sql_exp = ""
## otherwise get a random selection
else:
## get a list of all OIDs
oid_list = [row[0] for row in arcpy.da.SearchCursor(in_features, oid_fld)]
## get a random list of OIDs
random_list = random.sample(oid_list, number_of_points)
## create the where clause sql expression
sql_exp = "{0} IN ({1})".format(oid_fld, ",".join(str(x) for x in random_list))
## start an insert cursor for the temp_fc
with arcpy.da.InsertCursor(temp_fc, ["ORIG_FID", "SHAPE@"]) as insert_cursor:
## iterate through the records of the in_features
with arcpy.da.SearchCursor(in_features, [oid_fld, "SHAPE@"], sql_exp) as search_cursor:
## add the points to the temp_fc
for row in search_cursor:
insert_cursor.insertRow((row[0], row[1]))
elif shape_type == "Polyline":
## start an insert cursor for the temp_fc
with arcpy.da.InsertCursor(temp_fc, ["ORIG_FID", "SHAPE@"]) as insert_cursor:
## iterate through the records for the in_features
with arcpy.da.SearchCursor(in_features, [oid_fld, "SHAPE@", "SHAPE@LENGTH"]) as search_cursor:
## for each linear record
for row in search_cursor:
## generate a random point along the line and add to temp_fc
for num in range(number_of_points):
distance = round(random.uniform(0.0, row[2]), 3)
pt = row[1].positionAlongLine(distance)
insert_cursor.insertRow((row[0], pt))
elif shape_type == "Polygon":
## start an insert cursor for the temp_fc
with arcpy.da.InsertCursor(temp_fc, ["ORIG_FID", "SHAPE@"]) as insert_cursor:
## iterate through the records for the in_features
with arcpy.da.SearchCursor(in_features, [oid_fld, "SHAPE@"]) as search_cursor:
## for each polygon record
for row in search_cursor:
## to hold random points
random_points = []
## get the extent of the feature
extent = row[1].extent
min_x, max_x = extent.XMin, extent.XMax
min_y, max_y = extent.YMin, extent.YMax
## generate points
for num in range(number_of_points):
while len(random_points) < number_of_points:
x = random.uniform(min_x, max_x)
y = random.uniform(min_y, max_y)
pt = arcpy.Point(x, y)
## if the point is inside the polygon then add to the list
if row[1].contains(pt):
random_points.append(pt)
## insert points into the temp_fc
for pt in random_points:
insert_cursor.insertRow((row[0], pt))
Export the random generated points in our memory feature class to disk.
## export random generated points to a feature class on disk
arcpy.conversion.ExportFeatures(temp_fc, out_feature_class)
And as always, clean-up the memory workspace.
## clean-up memory workspace
arcpy.management.Delete(temp_fc)
Save your script and open up ArcGIS Pro. Right-click on your toolbox/toolset of choice and select New > Script. The New Script window will appear. In the General tab set Name to createRandomPoints, Label to Create Random Points (Basic), and the Description to Create Random Points with a Basic License.
In the Parameters tab set as per below. Set the Filter for Input Features to Feature Type; Point, Polyline, Polygon. Set the Direction for Output Feature Class to Output and a Filter for Feature Type of Point.
In the Execution tab, click the folder icon in the top-right corner and ad your saved Python script. Click OK and take the tool for a spin.
You can download the tool and other Advanced tools with a Basic license over on this page.
Here’s the Create Random Points script in its entirety.
import arcpy
import random
################################################################################
## Esri Documentation
## https://pro.arcgis.com/en/pro-app/latest/arcpy/functions/getparameterastext.htm
## https://pro.arcgis.com/en/pro-app/latest/arcpy/functions/describe.htm
## https://pro.arcgis.com/en/pro-app/latest/arcpy/functions/listfields.htm
## https://pro.arcgis.com/en/pro-app/latest/tool-reference/data-management/add-field.htm
## https://pro.arcgis.com/en/pro-app/latest/tool-reference/data-management/create-feature-class.htm
## https://pro.arcgis.com/en/pro-app/latest/arcpy/classes/polyline.htm
## https://pro.arcgis.com/en/pro-app/latest/arcpy/classes/polygon.htm
## https://pro.arcgis.com/en/pro-app/latest/tool-reference/data-management/get-count.htm
## https://pro.arcgis.com/en/pro-app/latest/arcpy/data-access/searchcursor-class.htm
## https://pro.arcgis.com/en/pro-app/latest/arcpy/data-access/updatecursor-class.htm
## https://pro.arcgis.com/en/pro-app/latest/tool-reference/conversion/export-features.htm
## https://pro.arcgis.com/en/pro-app/latest/tool-reference/data-management/delete.htm
##
## ArcGIS Pro Version: 3.1.0
##
################################################################################
################################################################################
## USER INPUTS
## the input features to generate random points for
in_features = arcpy.GetParameterAsText(0)
## the output point feature class
out_feature_class = arcpy.GetParameterAsText(1)
## the number of points to generate for each feature
number_of_points = arcpy.GetParameterAsText(2)
################################################################################
## REQUIRED OBJECTS
## shape type of in features - Point, Polygon, Polyline
shape_type = arcpy.Describe(in_features).shapeType
## srs id of the in_features so we can assign the output the same
srs_id = arcpy.Describe(in_features).spatialReference.factoryCode
## the OID field name from the in_features
oid_fld = [fld.name for fld in arcpy.ListFields(in_features) if fld.type=="OID"][0]
## make sure the number of points is an integer
number_of_points = int(number_of_points)
################################################################################
## CREATE POINT FEATURE CLASS IN MEMORY WORKSPACE
## a memory workspace feature class to store the random points generated
temp_fc = arcpy.management.CreateFeatureclass("memory", "temp_fc", "POINT", spatial_reference=srs_id)
## add ORIG_FID field to teh feature class
arcpy.management.AddField(temp_fc, "ORIG_FID", "LONG")
################################################################################
## CREATE RANDOM POINTS
## if the in_features are Points
if shape_type == "Point":
num_points = int(arcpy.management.GetCount(in_features)[0])
## if the number of random points required is more than the points in in_features
if number_of_points >= num_points:
## no need for a where clause if the number of points from user input
## matches or exceeds the number of points in the in_features
sql_exp = ""
## otherwise get a random selection
else:
## get a list of all OIDs
oid_list = [row[0] for row in arcpy.da.SearchCursor(in_features, oid_fld)]
## get a random list of OIDs
random_list = random.sample(oid_list, number_of_points)
## create the where clause sql expression
sql_exp = "{0} IN ({1})".format(oid_fld, ",".join(str(x) for x in random_list))
## start an insert cursor for the temp_fc
with arcpy.da.InsertCursor(temp_fc, ["ORIG_FID", "SHAPE@"]) as insert_cursor:
## iterate through the records of the in_features
with arcpy.da.SearchCursor(in_features, [oid_fld, "SHAPE@"], sql_exp) as search_cursor:
## add the points to the temp_fc
for row in search_cursor:
insert_cursor.insertRow((row[0], row[1]))
elif shape_type == "Polyline":
## start an insert cursor for the temp_fc
with arcpy.da.InsertCursor(temp_fc, ["ORIG_FID", "SHAPE@"]) as insert_cursor:
## iterate through the records for the in_features
with arcpy.da.SearchCursor(in_features, [oid_fld, "SHAPE@", "SHAPE@LENGTH"]) as search_cursor:
## for each linear record
for row in search_cursor:
## generate a random point along the line and add to temp_fc
for num in range(number_of_points):
distance = round(random.uniform(0.0, row[2]), 3)
pt = row[1].positionAlongLine(distance)
insert_cursor.insertRow((row[0], pt))
elif shape_type == "Polygon":
## start an insert cursor for the temp_fc
with arcpy.da.InsertCursor(temp_fc, ["ORIG_FID", "SHAPE@"]) as insert_cursor:
## iterate through the records for the in_features
with arcpy.da.SearchCursor(in_features, [oid_fld, "SHAPE@"]) as search_cursor:
## for each polygon record
for row in search_cursor:
## to hold random points
random_points = []
## get the extent of the feature
extent = row[1].extent
min_x, max_x = extent.XMin, extent.XMax
min_y, max_y = extent.YMin, extent.YMax
## generate points
for num in range(number_of_points):
while len(random_points) < number_of_points:
x = random.uniform(min_x, max_x)
y = random.uniform(min_y, max_y)
pt = arcpy.Point(x, y)
## if the point is inside the polygon then add to the list
if row[1].contains(pt):
random_points.append(pt)
## insert points into the temp_fc
for pt in random_points:
insert_cursor.insertRow((row[0], pt))
################################################################################
## SAVE MEMORY FEATURE CLASS TO DISK
## export random generated points to a feature class on disk
arcpy.conversion.ExportFeatures(temp_fc, out_feature_class)
################################################################################
## CLEAN-UP MEMORY WORKSPACE
## clean-up memory workspace
arcpy.management.Delete(temp_fc)
################################################################################