topic Re: Create fishnet in iterative model in ModelBuilder Questions

Create fishnet in iterative model

deleted-user-qQeebl6UEQjh — Tue, 19 Jul 2011 18:52:54 GMT

I wonder if anyone has any ideas on the following.

I am using Create Fishnet in an iterative model. The goal being to flip through all features in a feature class and create a fishnet from the bounding coordinates of each individual feature. Fishnet is fed from a feature layer denoted with the %n% keyword but the extents data does not update. The result is the same grid being created over and over again. Is there any way to ensure that the extents are being updated?

Re: Create fishnet in iterative model

deleted-user-qQeebl6UEQjh — Wed, 27 Jul 2011 18:34:00 GMT

Well I gave up on out of the box and came up with the script below to create fishnets. I am hoping to keep this as an iterative model where this script is passed the current %n% value from the model. Can anyone suggest how/if it is possible to pass the %n% value into a script using sys.argv[]? Using 9.2. Thanks.

# Import system modules
import sys, string, os, arcgisscripting

# Create the geoprocessor object
gp = arcgisscripting.create()
gp.overwriteOutput = 1

# Set workspace
gp.Workspace = "C:/CollapseTestModel.gdb"
myNet = "C:/CollapseTestModel.gdb/Net03"
myTemplate = "C:/CollapseTestModel.gdb/SelectBody__0"

dsc=gp.describe(myTemplate)

extents = dsc.Extent
print extent

gp.CreateFishnet_management(myNet,extents[0:17] + " " + extents[18:34],extents[0:17] + " 53", 0.000045, 0.000045, 50, 50, "#", "NO_LABELS", myTemplate)

print gp.GetMessages()

Re: Create fishnet in iterative model

TrevorSelf — Fri, 16 Dec 2011 17:34:38 GMT

I wonder if anyone has any ideas on the following.

I am using Create Fishnet in an iterative model. The goal being to flip through all features in a feature class and create a fishnet from the bounding coordinates of each individual feature. Fishnet is fed from a feature layer denoted with the %n% keyword but the extents data does not update. The result is the same grid being created over and over again. Is there any way to ensure that the extents are being updated?

I am having this same problem! It appears, by looking through the log, that the extent is set before the file that sets the extent is fed into the fishnet tool. I'm thinking about trying to get the corners of the extent with minimum bounding geometry and feature vertices to point tools, but it might add several steps to the model.

Re: Create fishnet in iterative model

DanLee — Fri, 16 Dec 2011 20:10:29 GMT

Perhaps before Create Fishnet you can use Copy Features to copy a selected feature to a feature class or an in_memory feature class (if you don't need to save it); and then feed this feature class to the Template extent. I think this would make the extent update in each iteration.

Re: Create fishnet in iterative model

TrevorSelf — Wed, 21 Dec 2011 17:13:25 GMT

Dan,
Thanks for replying so quickly. I have tried this suggestion exactly. I have a separate model to iterate through a feature class and copy out individual features into their own feature classes, but the create fishnet tool ends up just creating many fishnets on top of each other (one for each feature in the geodatabase). When checking through the log, as the feature classes iterate, they are input into each iteration in the create fishnet tool, but the extents never update to the extents of each feature class

Re: Create fishnet in iterative model

NobbirAhmed — Sun, 12 Dec 2021 10:47:42 GMT

The whole thing can be done in Python. Here is a sample code (not tested on 9.2):

import arcgisscripting
 
gp = arcgisscripting.create()
gp.overwriteOutput = 1

# input hard-coded but you can make it a script tool parameter to make it an interactive input.
in_fc = r"C:\temp\f.gdb\curvepoly"  # this polygon feature class has several polygons.
 
rows = gp.SearchCursor(in_fc)
row = rows.Next()

while row:
    feat = row.shape
    ext = feat.extent
    orig = str(ext.XMin) + " " + str(ext.YMin)
    yaxis = str(ext.XMin) + " " + str(ext.YMin + 100.00)
    opp_corner = str(ext.XMax) + " " + str(ext.YMax)
    print orig, yaxis, opp_corner
 
    out_fc = r"C:\temp\f.gdb\fishnetall_" + str(row.OBJECTID)
 
    result = gp.CreateFishnet_management(out_fc, orig, yaxis, "0", "0", "5", "8", opp_corner)
    print(gp.GetMessages())

    row = rows.Next()

del row, rows

Re: Create fishnet in iterative model

DanLee — Wed, 11 Jan 2012 20:19:37 GMT

Dan,
Thanks for replying so quickly. I have tried this suggestion exactly. I have a separate model to iterate through a feature class and copy out individual features into their own feature classes, but the create fishnet tool ends up just creating many fishnets on top of each other (one for each feature in the geodatabase). When checking through the log, as the feature classes iterate, they are input into each iteration in the create fishnet tool, but the extents never update to the extents of each feature class

Thank you for letting me know. We have investigated this issue; there is indeed a bug in the tool that affects the extent update in iteration. If you can, please submit a change/fix request to Esri Support; we might get to it a bit quicker.

There is no easy workaround. Hope you can use the script Nobbir provided to get through the process. Sorry about the inconvenience.

Re: Create fishnet in iterative model

DanLee — Wed, 18 Jul 2012 23:22:14 GMT

Hi Señor and Trevor,

It's been a while; we will be looking into enhancements for the Create Fishnet tool. Both of you needed fishnets for individual features; could you describe why you want a fishnet per feature? What is the application/story? Your use cases would help us understand the requirements and provide the right solutions.

If you have any additional criteria about creating fishnet, please let me know. I appreciate your time and input.

Thanks a lot!

Re: Create fishnet in iterative model

ClemensHabsburg-Lothringen — Thu, 11 Oct 2012 06:16:56 GMT

Thank you for letting me know. We have investigated this issue; there is indeed a bug in the tool that affects the extent update in iteration. If you can, please submit a change/fix request to Esri Support; we might get to it a bit quicker.

There is no easy workaround. Hope you can use the script Nobbir provided to get through the process. Sorry about the inconvenience.

Could you already solve this problem? Or is there another way to workaround?
Thanks

Re: Create fishnet in iterative model

NobbirAhmed — Thu, 11 Oct 2012 14:22:54 GMT

We haven't made any changes to the tool. This tool won't work the way you want in ModelBuilder. There is a plan to create a new similar tool - but there is no tentative time-frame yet.

Have you tried my Python script? This may be the only workaround comes to my mind.

Re: Create fishnet in iterative model

DaleHoneycutt — Thu, 11 Oct 2012 15:26:09 GMT

There's a sample tool in the Analysis and Geoprocessing Gallery that may do what you need: http://www.arcgis.com/home/item.html?id=9398bd2232cb4c8490b0b05015364d28.

Re: Create fishnet in iterative model

MarkZweifler — Thu, 15 Nov 2012 10:39:22 GMT

Hi Señor and Trevor,

It's been a while; we will be looking into enhancements for the Create Fishnet tool. Both of you needed fishnets for individual features; could you describe why you want a fishnet per feature? What is the application/story? Your use cases would help us understand the requirements and provide the right solutions.

If you have any additional criteria about creating fishnet, please let me know. I appreciate your time and input.

Thanks a lot!

I am wanting to do this to create a nested hierarchical grid similar to the U.S. National Grid or Military Grid. So that I have a repeating 1-4 ( 2 * 2) grid for each cell at its next highest level in the nested hierarchy.

Re: Create fishnet in iterative model

MarkZweifler — Thu, 15 Nov 2012 14:31:08 GMT

As a non-Python guy I was able to devise a Model Builder workaround that involved coverting each iterated selected polygon to a raster subdivided into pixels at the desired size. Then through a series of steps converting that raster back to a polygon layer

see screenshot below

[ATTACH=CONFIG]19338[/ATTACH]

Re: Create fishnet in iterative model

curtvprice — Sat, 17 Nov 2012 01:25:03 GMT

I had a different solution to get around the not-so-helpful extent handling in ModelBuilder iteration:

I used Calculate Value to extract the extent and then split that result to calculate the other parameters for the Create Fishnet tool.

Here are two of the Calculate Value setups and how I put the model together. Note I added some grace area around the extent (hence the complicated math):

[ATTACH=CONFIG]19389[/ATTACH][ATTACH=CONFIG]19390[/ATTACH]

[ATTACH=CONFIG]19391[/ATTACH]

Re: Create fishnet in iterative model

nedamohammadi1 — Thu, 21 Mar 2013 13:13:39 GMT

Dear Esri member,
thank you so much for this code, I exactly used this , but still I have problem with this error:
'str' object has no attribute 'XMin'
could you help me?I want to build a model for creat fishnet for several raster files ..

regards

Nedaaa

Re: parsing extent: 'str' object has no attribute 'XMin'

curtvprice — Sun, 12 Dec 2021 10:47:45 GMT

I exactly used this , but still I have problem with this error:
'str' object has no attribute 'XMin'

Sorry about that, here's an example of the code that does not work (it worked at 9.x):

def Origin(ext):
  ext = ext.split()
  return "%s %s" % (ext[0], ext[1])

Since extent is now handled as a full-fledged object, you can fix this code by either converting it to a string:

def Origin(ext):
  ext = str(ext).split()
  return "%s %s" % (ext[0], ext[1])

or requesting the extent object properties directly (probably the best way):

def Origin(ext):
  return "%s %s" % (ext.XMin, ext.YMin)