Updated Class 10

Author: marecotec

Classes/10_Cursors/Step_4.py

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+
+#####
+# Step 4 - Data Access module - Adding new records using an InsertCursor.
+#####
+
+# Insert Cursors are uised to add new data to shapefile or feature class. It is almost exactly the same
+# as the other Cursors that we have used. In this example, we will construct a line feature class.
+
+import arcpy, os
+from math import radians, sin, cos
+
+# Create an empty Shapefile
+arcpy.env.workspace = r"Z:\Andy's Documents\Teaching and students\URI\NRS - GIS Python Course\Github\Course_ArcGIS_Python\Classes\10_Cursors"
+
+# Set local variables
+out_path = arcpy.env.workspace
+out_name = "radiating_line.shp"
+geometry_type = "POLYLINE"
+template = "#"
+has_m = "DISABLED"
+has_z = "DISABLED"
+
+# Use Describe to get a SpatialReference object
+spatial_ref = 4326
+
+# Execute CreateFeatureclass
+arcpy.CreateFeatureclass_management(out_path, out_name, geometry_type, template,
+                                    has_m, has_z, spatial_ref)
+
+
+# From a point (origin), let's create some radiating lines and add them to the new shapefile
+
+origin_x, origin_y = (-71.42,  41.47)
+distance = 1
+angle = 10  # in degrees
+
+OutputFeature = os.path.join(out_path, out_name)
+
+#create list of bearings
+angles = range(0, 360,angle)
+
+
+for ang in angles:
+    # calculate offsets with  trig
+    angle = float(int(ang))
+    (disp_x, disp_y) = (distance * sin(radians(angle)), distance * cos(radians(angle)))
+    (end_x, end_y) = (origin_x + disp_x, origin_y + disp_y)
+    (end2_x, end2_y) = (origin_x + disp_x, origin_y + disp_y)
+
+    cur = arcpy.InsertCursor(OutputFeature)
+    lineArray = arcpy.Array()
+
+    # start point
+    start = arcpy.Point()
+    (start.ID, start.X, start.Y) = (1, origin_x, origin_y)
+    lineArray.add(start)
+
+    # end point
+    end = arcpy.Point()
+    (end.ID, end.X, end.Y) = (2, end_x, end_y)
+    lineArray.add(end)
+
+    # write our fancy feature to the shapefile
+    feat = cur.newRow()
+    feat.shape = lineArray
+    cur.insertRow(feat)
+
+	# yes, this shouldn't really be necessary...
+    lineArray.removeAll()
+    del cur
+
+
+# Task - Using the above code, amend it so you can do multiple origin_x and origin_y. Note that you don't have to do
+# too much to the code, so think of the steps you need to take before you touch this. BTW this is a hard one. Use this
+# for your input locations: input_locations = [(-71.42,  41.47), (-72.42,  42.47), (-73.42,  43.47)]
+

Classes/10_Cursors/Step_4_Answers.py

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+
+#####
+# Step 4 - Data Access module - Adding new records using an InsertCursor.
+#####
+
+# Insert Cursors are uised to add new data to shapefile or feature class. It is almost exactly the same
+# as the other Cursors that we have used. In this example, we will construct a line feature class.
+
+import arcpy, os
+from math import radians, sin, cos
+
+# Create an empty Shapefile
+arcpy.env.workspace = r"Z:\Andy's Documents\Teaching and students\URI\NRS - GIS Python Course\Github\Course_ArcGIS_Python\Classes\10_Cursors"
+
+# Set local variables
+out_path = arcpy.env.workspace
+out_name = "radiating_line.shp"
+geometry_type = "POLYLINE"
+template = "#"
+has_m = "DISABLED"
+has_z = "DISABLED"
+
+# Use Describe to get a SpatialReference object
+spatial_ref = 4326
+
+# Execute CreateFeatureclass
+arcpy.CreateFeatureclass_management(out_path, out_name, geometry_type, template,
+                                    has_m, has_z, spatial_ref)
+
+
+# From a point (origin), let's create some radiating lines and add them to the new shapefile
+
+origin_x, origin_y = (-71.42,  41.47)
+distance = 1
+angle = 10  # in degrees
+
+OutputFeature = os.path.join(out_path, out_name)
+
+#create list of bearings
+angles = range(0, 360,angle)
+
+
+for ang in angles:
+    # calculate offsets with  trig
+    angle = float(int(ang))
+    (disp_x, disp_y) = (distance * sin(radians(angle)), distance * cos(radians(angle)))
+    (end_x, end_y) = (origin_x + disp_x, origin_y + disp_y)
+    (end2_x, end2_y) = (origin_x + disp_x, origin_y + disp_y)
+
+    cur = arcpy.InsertCursor(OutputFeature)
+    lineArray = arcpy.Array()
+
+    # start point
+    start = arcpy.Point()
+    (start.ID, start.X, start.Y) = (1, origin_x, origin_y)
+    lineArray.add(start)
+
+    # end point
+    end = arcpy.Point()
+    (end.ID, end.X, end.Y) = (2, end_x, end_y)
+    lineArray.add(end)
+
+    # write our fancy feature to the shapefile
+    feat = cur.newRow()
+    feat.shape = lineArray
+    cur.insertRow(feat)
+
+	# yes, this shouldn't really be necessary...
+    lineArray.removeAll()
+    del cur
+
+
+# Task - Using the above code, amend it so you can do multiple origin_x and origin_y. Note that you don't have to do
+# too much to the code, so think of the steps you need to take before you touch this. BTW this is a hard one. Use this
+# for your input locations: input_locations = [(-71.42,  41.47), (-72.42,  42.47), (-73.42,  43.47)]
+
+import arcpy, os
+from math import radians, sin, cos
+
+# Create an empty Shapefile
+arcpy.env.workspace = r"Z:\Andy's Documents\Teaching and students\URI\NRS - GIS Python Course\Github\Course_ArcGIS_Python\Classes\10_Cursors"
+
+# Set local variables
+out_path = arcpy.env.workspace
+out_name = "radiating_line_2.shp"
+geometry_type = "POLYLINE"
+template = "#"
+has_m = "DISABLED"
+has_z = "DISABLED"
+
+# Use Describe to get a SpatialReference object
+spatial_ref = 4326
+
+# Execute CreateFeatureclass
+arcpy.CreateFeatureclass_management(out_path, out_name, geometry_type, template,
+                                    has_m, has_z, spatial_ref)
+
+
+input_locations = [(-71.42,  41.47), (-72.42,  42.47), (-73.42,  43.47)]
+
+for i in input_locations:
+
+
+    origin_x, origin_y = i[0], i[1]
+    distance = 1
+    angle = 10  # in degrees
+
+    OutputFeature = os.path.join(out_path, out_name)
+
+    #create list of bearings
+    angles = range(0, 360,angle)
+
+
+    for ang in angles:
+        # calculate offsets with  trig
+        angle = float(int(ang))
+        (disp_x, disp_y) = (distance * sin(radians(angle)), distance * cos(radians(angle)))
+        (end_x, end_y) = (origin_x + disp_x, origin_y + disp_y)
+        (end2_x, end2_y) = (origin_x + disp_x, origin_y + disp_y)
+
+        cur = arcpy.InsertCursor(OutputFeature)
+        lineArray = arcpy.Array()
+
+        # start point
+        start = arcpy.Point()
+        (start.ID, start.X, start.Y) = (1, origin_x, origin_y)
+        lineArray.add(start)
+
+        # end point
+        end = arcpy.Point()
+        (end.ID, end.X, end.Y) = (2, end_x, end_y)
+        lineArray.add(end)
+
+        # write our fancy feature to the shapefile
+        feat = cur.newRow()
+        feat.shape = lineArray
+        cur.insertRow(feat)
+
+        # yes, this shouldn't really be necessary...
+        lineArray.removeAll()
+        del cur