topic Re: shifting features in Python Questions

shifting features

WendyRolston — Thu, 15 Jan 2015 17:05:25 GMT

I am totally new to script writing and am trying to get the Shifting Features code to work from ArcPy Café. I can't see what I am doing wrong.

Re: shifting features

DarrenWiens2 — Sun, 12 Dec 2021 03:18:28 GMT

You need to actually call the shift_features function. As it is, the script executes line 1, then executes line 3, then stops. Everything between 'def' and 'return' is a function just waiting to be called. Your script should look like this:

import arcpy
in_features = r"C:/Temp/CP_C06.shp"
x_shift = 20 # may as well shift by some number
y_shift = 50 # ditto

def shift_features(in_features, x_shift, y_shift):
  with arcpy.da_UpdateCursor(in_features, ['SHAPE@XY']) as cursor:
    for row in cursor:
      cursor.updateRow([[row[0][0] + (x_shift or 0), row[0][1] + (y_shift or 0)]])
  return

shift_features(in_features, x_shift, y_shift)

Also, please read "Posting Code Blocks in the New GeoNet" so we can copy/paste your code to help.

Re: shifting features

WendyRolston — Thu, 15 Jan 2015 23:03:16 GMT

Using PythonWin gives me the following error.

NameError: name 'shift_features' is not defined. Below is the code that I used.

import arcpy

in_features = r"C:/Temp/CP_C06.shp"
x_shift = 100
y_shift = 100
shift_features(in_features, x-shift, y_shift)

def shift_features (in_features, x_shift=None, y_shift=None):

    with arcpy.da.UpdateCursor(in_features, ['SHAPE@XY']) as cursor:
        for row in cursor:
            cursor.updateRow([[row[0][0] + (x_shift or 0),
                              row[0][1] + (y_shift or 0)]])

return

Re: shifting features

DarrenWiens2 — Thu, 15 Jan 2015 23:08:26 GMT

That's my fault. Move the function above the call to the function and it should work. I edited my post above.

Also, just a note about your script, you set a value of 100 for x and y shift, and then set both to None in the function definition. So, I would not expect any shift to be observed as it is.

Re: shifting features

WendyRolston — Thu, 15 Jan 2015 23:15:22 GMT

That totally did the trick. Thanks for helping the newbie.

Re: shifting features

DanPatterson_Retired — Thu, 15 Jan 2015 23:15:58 GMT

nice...Darren...although it would be wise to recommend that users experiment on a temporary file or use copyfeatures_management to clone an existing one prior to doing anything with shape geometry...a bad change in geometry can render a file useless

Re: shifting features

DarrenWiens2 — Thu, 15 Jan 2015 23:19:52 GMT

I figure if you're clever enough to play around with Python, you should be clever enough to make a backup or suffer the consequences.

Re: shifting features

DanPatterson_Retired — Thu, 15 Jan 2015 23:30:40 GMT

hahaha ... you have never taught then

Re: shifting features

WendyRolston — Tue, 14 Apr 2015 15:41:00 GMT

Hi Darren. What if I want to pull the x-shift value and y-shift value from a field in my shapefile instead of putting a value into the code sequence?

Re: shifting features

DarrenWiens2 — Sun, 12 Dec 2021 03:18:31 GMT

You can access field values by including them in the UpdateCursor. The list, ['SHAPE@XY','X_SHIFT','Y_SHIFT'] (change X_SHIFT and Y_SHIFT to your field names), translates to row[0], row[1], and row[2], respectively.

import arcpy
in_features = r"C:/Temp/CP_C06.shp"

def shift_features(in_features):
  with arcpy.da_UpdateCursor(in_features, ['SHAPE@XY','X_SHIFT','Y_SHIFT']) as cursor:
    for row in cursor:
      cursor.updateRow([[row[0][0] + (row[1] or 0), row[0][1] + (row[2] or 0)]])
  return

shift_features(in_features)

Re: shifting features

WendyRolston — Sun, 12 Dec 2021 03:18:34 GMT

Sorry, I am just not getting it. I have two fields. One is called x_shift and one is called y_shift. Both float fields. Each currently have a value of 200. I keep getting an error.

import arcpy
in_features = r"C:/Temp/CP_C06.shp"
def shift_features (in_features):
    
    with arcpy.da.UpdateCursor(in_features, ['SHAPE@XY','x_shift','y_shift']) as cursor:
        for row in cursor:
            cursor.updateRow([[row[0][0] + (row[1] or 0), row[0][1] + (row[2] or 0)]])
            
    return
shift_features(in_features)

Re: shifting features

DanPatterson_Retired — Tue, 14 Apr 2015 18:06:33 GMT

EDIT

Never mind...need the error message please

Re: shifting features

WendyRolston — Tue, 14 Apr 2015 18:25:30 GMT

Traceback (most recent call last):

File "C:\Python27\ArcGIS10.2\Lib\site-packages\pythonwin\pywin\framework\scriptutils.py", line 326, in RunScript

exec codeObject in __main__.__dict__

File "C:\Student\Script_fieldname.py", line 13, in <module>

shift_features(in_features)

File "C:\Student\Script_fieldname.py", line 9, in shift_features

cursor.updateRow([[row[0][0] + (row[1] or 0), row[0][1] + (row[2] or 0)]])

TypeError: sequence size must match size of the row

>>>

I'm working on a project that, in the past, I ran a move calculation [SHAPE].Move([fieldname],0) in arc3.3. I work in ArcGIS 10, but use the oldie for a couple of tasks. We have upgraded and now don't have the use of arc3.3 anymore. I need to find a (modern) way to shift polygon features way out of their original spatial placement and then back again. Arcpy Café "shifting features" coding looked promising, but way out of my wheelhouse. So I am here begging for help. I did some Python tutorials, but am just not getting it.

Wendy

Re: shifting features

AngelaBlanco — Thu, 09 Feb 2017 20:50:09 GMT

Hi Dan,

I am trying to shift points using the function shift_features, but i am getting this error:

Runtime error
Traceback (most recent call last):
File "<string>", line 10, in <module>
File "<string>", line 5, in shift_features
AttributeError: 'module' object has no attribute 'da_UpdateCursor'

import arcpy
in_features =r"B14_20140416_Mornings_UTM32"

def shift_features(in_features):
with arcpy.da_UpdateCursor(in_features, ['SHAPE@XY','NEAR_X','NEAR_Y']) as cursor:
for row in cursor:
cursor.updateRow([[row[0][0] + (row[1] or 0), row[0][1] + (row[2] or 0)]])
return

shift_features(in_features)

I am working on a FileGDB with ArcGIS 10.3

NEAR_X and NEAR_Y are attributes of B14_20140416_Mornings_UTM32"

Thanks for the help

Re: shifting features

AngelaBlanco — Thu, 09 Feb 2017 20:56:28 GMT

I got a new error:

Runtime error
Traceback (most recent call last):
File "<string>", line 7, in <module>
File "<string>", line 4, in shift_features
TypeError: sequence size must match size of the row

Re: shifting features

DanPatterson_Retired — Thu, 09 Feb 2017 21:08:37 GMT

Angela, it is working from a table in arcmap and not a file on disc and you need the associated other fields in the table besides the shapefield. You would provide the function with the layer's name in the shift_features call,

Re: shifting features

AngelaBlanco — Thu, 09 Feb 2017 21:30:02 GMT

Thank Dan for the quick answer. Could you provide me an example what I should include?

in_features ="B14_20140416_Mornings_UTM32" is a FeatureClass with points. It contains the Attributes NEAR_X and NEAR_Y.

Best regards,

Angela

Re: shifting features

DanPatterson_Retired — Sun, 12 Dec 2021 03:18:36 GMT

Angela... to be on the safe side, I hate messing with existing geometry...

Since your data are in a table already, then it would be far safer to add 2 new fields New_X and New_Y (double) and simply use the field calculator to calculate new values for the point in those fields then use File,Add data, add XY data just like you would for any event theme. (ie New_X would equal !SHAPE! + !Your_X_Shift_Field! ... and similarly for Y

There is a field calculator example which could be modified, if you want to experiment... on a copy... NOTE, totally untested so work on a copy of the file... making my original suggestion even better... but give it a try later when you have time or want to experiment.

Let me know if it works, It will be some time before I am on an Arc* machine.

# code block... python parser

def shape_shifter(shape, shift_x=0, shift_y=0):
    """provide the shift_x and shift_y fields"""
    point = shape.getPart(0)
    point.X += shift_X
    point.Y += shift_Y
    return point

# expression box...
# shape_shifter(!SHAPE!, !X_shift_fld!, !Y_shift_fld!)
# presumably on the Shape field in the field calculator
‍‍‍‍‍‍‍‍‍‍‍‍

that can be modified

Re: shifting features

AngelaBlanco — Fri, 10 Feb 2017 14:57:25 GMT

Thanks Dan,

I created the new fields how you mencioned and the calculated the new position for every point. Then I used arcpy.MakeXYEventLayer_management and saved it in a new feature.

Now it works.

Best regards

Ángela