Latest Contributions by DarrenWiens2

Richard, the units for positionAlongLine are determined by the spatial reference of the Polyline object. For example, the following snippet places a point 1000 feet from the start of the line, because "kentucky_line" uses the Kentucky State Plane US Feet projection: >>> for row in arcpy.da.SearchCursor("kentucky_line", ["SHAPE@"]): ...     point = row[0].positionAlongLine(1000) >>> arcpy.CopyFeatures_management(point, 'in_memory\point') ... View more

Josh, positionAlongLine defaults to using an absolute distance. If you want to use a percentage, you would change the optional second parameter to True (I think). Richard, this is clearly just one method, and for me using Python geometry objects is more flexible than finding the fastest pre-made tool. IMHO, it also directly answers the question, "how do I create points along a polyline based on distance," better than "read the help on Linear Referencing". ... View more

Back to the original question, you can fairly easily place a point along a line at a feature-specific distance using arcpy geometry objects - specifically, the positionAlongLine method in the Polyline object. positionAlongLine (value, {use_percentage}) Returns a point on a line at a specified distance from the beginning of the line. ... View more

Along the lines of Vince's suggestion, here is a python script that goes most of the way there. The script below is a python script tool - change polyFC and outBuffs to file paths of your choice. The algorithm is more coarse than what Vince suggests - it merely shrinks the buffers by the distance specified in the increment variable, until it passes the threshold specified in the testPercent variable. The use of geometry objects allows for buffers on a feature by feature basis. # import libraries import arcpy # set input/output parameters polyFC = arcpy.GetParameterAsText(0)    # input polygons outBuffs = arcpy.GetParameterAsText(1)  # output interior buffers # percentage of interest testPercent = 0.35 # increment to shrink buffers increment = -0.1 # e.g. 10cm # buffers container buffs = [] def negBuff(geom, dist, origArea):     # apply negative buffer     buffGeom = geom.buffer(dist)     buffArea = buffGeom.area     # test against percentage of interest     # if less than percentage, add to array     # if not, increase buffer and try again     if buffArea/origArea < testPercent:         buffs.append(buffGeom)         pass     else:         negBuff(geom, dist + increment, origArea) for row in arcpy.da.SearchCursor(polyFC, ["SHAPE@"]):     # calculate original area     origArea = row[0].area     # run buffers     negBuff(row[0], increment, origArea) # persist geometry objects arcpy.CopyFeatures_management(buffs, outBuffs) ... View more

You could make 8 copies of your raster (Copy Raster), position each one to surround your original raster using the Shift tool, mosaic these 9 raster together (Mosaic to New Raster), and run Focal Statistics on this new raster. Finally, clip out the original raster using the method of your choice (Con, perhaps). ... View more

My personal opinion is that if you don't have a reason to use a geodatabase, don't. There are many special reasons to use GDBs (domains, networks, etc.), but the hassles of sharing data with unknown users (with unknown ArcGIS version, or none at all) is prohibitive for me. ... View more

As Owen alludes to, make sure your data is first defined correctly (according to the original data) and then projected properly, if necessary. See this Knowledge Base article: When do I define a projection, and when do I project data? ... View more

You should be able to use Tool Validation for this. Also, see here for a working example, employing an arcpy.da.SearchCursor. ... View more

Thank you! It goes to show that taking a step back can lend some clarity. In the end, I had misdiagnosed my problem, but your example definitely helped. The problem was in how I was re-writing the geometry. The major difference in my working script (below) and yours is that mine takes along all (an unknown number) of fields and writes them to the new geometry. I had been assigning the row[0].centroid coordinates to the SHAPE@XY token, but it was later overwritten by the shape value coming in with all fields ('*'). At least, I think that's what was going on... # import libraries import arcpy, os # set input/output parameters polyFC = arcpy.GetParameterAsText(0) outCentroids = arcpy.GetParameterAsText(1) # set overwrite environment arcpy.env.overwriteOutput = True # if the output file does not exist, create it. Add "ORIG_ID" field. if not arcpy.Exists(outCentroids):     arcpy.CreateFeatureclass_management(os.path.dirname(outCentroids),                                     os.path.basename(outCentroids),                                     "POINT",                                     polyFC,                                     "",                                     "",                                     polyFC)     arcpy.AddField_management(outCentroids,'ORIG_ID', 'LONG') # create an InsertCursor containing all the fields in ourCentroids, which are all the fields in polyFC plus "ORIG_ID" cursor = arcpy.da.InsertCursor(outCentroids, ['*']) # read all features in polyFC for row in arcpy.da.SearchCursor(polyFC, ["SHAPE@",'*','OID@']):      # create an array to hold a new, modified row     rowArray = []      # read all the fields except "SHAPE@"     for fieldnum in range(1,len(row)):         # if this is the second field [i.e. SHAPE], replace it with the centroid coordinates         if fieldnum == 2:             rowArray.append(row[0].centroid)         else:             rowArray.append(row[fieldnum])     # write the new row to the cursor     cursor.insertRow(rowArray) del row ... View more

Thanks, Dan, although I'm reading the exact same help files. ...and I get the same result for centroid, trueCentroid, and labelPoint. I'll admit I am not fully comfortable accessing geomtries with tokens - could this be the source of the issue? I've produced the same result (centroid outside of polygons) with both SHAPE@ and SHAPE@XY. ... View more

Thanks for the replies, but still "no." It is my understanding that "centroid" is supposed to return the labelPoint in the event that the first returned point does not fall inside the polygon. Here is the updated, still not working, code: # import libraries import arcpy, os # set input/output parameters polyFC = arcpy.GetParameterAsText(0) outCentroids = arcpy.GetParameterAsText(1) # set overwrite environment arcpy.env.overwriteOutput = True # if the output file does not exist, create it. Add "ORIG_ID" field. if not arcpy.Exists(outCentroids):     arcpy.CreateFeatureclass_management(os.path.dirname(outCentroids),                                     os.path.basename(outCentroids),                                     "POINT",                                     polyFC,                                     "",                                     "",                                     polyFC)     arcpy.AddField_management(outCentroids,'ORIG_ID', 'LONG') # collect all of the polygon centroids into an array pointArray = [] for row in arcpy.da.SearchCursor(polyFC, ["SHAPE@",'*','OID@']):     rowArray = []     rowArray.append(row[0].labelPoint)     for field in range(1,len(row)):         rowArray.append(row[field])     pointArray.append(rowArray) del row # write the centroids to the output file cursor = arcpy.da.InsertCursor(outCentroids, ["SHAPE@",'*']) for point in pointArray:     arcpy.AddMessage(point)     cursor.insertRow(point) del cursor ... View more