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Arcpy -- Edit Spatial Reference Object Properties

TrilliumLevine1

Hello All,

I'm trying to develop a python script to edit the name property of several spatial reference objects found while iterating through a folder and its subdirectories. The projection of the data is identical to ETRS_1989_UTM_Zone_32N, but is named something else -- I'm just trying to reset the name to ETRS_1989_UTM_Zone_32N. According to the help, this property is both readable and writable in ArcGIS 10.2, which is what I'm running. I'm just not sure how to go about writing in the new projection name via the script...anybody have any ideas? Any feedback is greaty appreciated!

Here's my code so far:

import os
import arcpy

workspace = r"C:\Scripts\Reproject"
newProjection = "ETRS_1989_UTM_Zone_32N"

def recursiveProjections(workspace):
    """
    Function iterates through a workspace and its subfolders using arcpy.da.walk and returns
    a list of spatial reference objects of all geographic datasets (including those inside
    geodatabases).  Parameter: target workspace

    """
    projections = []
    for dirpath, dirnames, filenames in arcpy.da.Walk(workspace):
        for filename in filenames:
            desc = arcpy.Describe(os.path.join(dirpath, filename))
            srObject = desc.spatialReference
            projections.append(srObject)
    return projections

def editProjection(workspace):
    projections = recursiveProjections(workspace)
    for projection in projections:
        print projection.name

editProjection(workspace)

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Accepted answers

AndrewLowerre

Hi Trillium,

Perhaps the 'Define Projection' tool (ArcGIS Help (10.2, 10.2.1, and 10.2.2) ) is what you're after?

If I understand you correctly, you want to walk over all the feature classes in a workspace and change the Spatial Reference for each one to ETRS_1989_UTM_Zone_32N. 'Define Projection' should enable you to do that.

Hope this helps,

Andrew

All comments

TrilliumLevine1

Hi Marco,

Sorry for the late answer, here's what I ended up with that works, hope it's helpful -- does a bit of logging for you too:

# -*- coding: utf-8 -*-
import os
from os import path
import arcpy
from arcpy import env
from sets import Set
import time, datetime
from datetime import date

arcpy.env.overwriteOutput = True
newProjection = arcpy.SpatialReference(25832) # wkid for 'ETRS_1989_UTM_Zone_32N'

# ################### #
#      FUNCTIONS      #
# ################### #

def recursiveDatasets(workspace):
    """
    Function iterates through a workspace and its subfolders using arcpy.da.walk and returns
    a list of spatial reference objects of all geographic datasets (including those inside
    geodatabases).  Parameter: target workspace

    """
    paths = []
    uniquePaths = []
    for dirpath, dirnames, filenames in arcpy.da.Walk(workspace):
        for filename in filenames:
            desc = arcpy.Describe(os.path.join(dirpath, filename))
            if hasattr(desc, 'path'):
                descPth = arcpy.Describe(desc.path)
            if hasattr(descPth, 'dataType'):
                # return list of FD paths and FC paths not in FD's
                if descPth.dataType == 'FeatureDataset':
                    paths.append(dirpath)
                elif desc.datasetType == 'FeatureClass':
                    paths.append(os.path.join(dirpath, filename))
    # make list without duplicates
    uniquePaths = list(set(paths))
    return uniquePaths


def defineProjection(workspace, toRedefine):
    """ Function redefines datasets in a given projection in a geodatabase.  Parameters: workspace, projection to consider
    """
    paths = recursiveDatasets(workspace)
    for path in paths:
        # create a description object for every dataset (incl. tables, relationship classes) not residing in FD
        desc = arcpy.Describe(path)
        if desc.spatialReference.Name == toRedefine:
            arcpy.management.DefineProjection(desc.Name, newProjection)
            print desc.Name + ' wurde neu definiert.'
        else:
            print desc.Name + ' wurde nicht neu definiert.'



def Logging(myLog, writeFormat, runDate, headers, list1, list2, colWdth):
    """ Function will generates a log file composed of two columns (list1 and list2) with defined
        headers and date of execution. Parameters: full log filepath, write format, date of execution,
        headers, list1, list2, column width
    """
    with open(myLog, writeFormat) as myLog:
        myLog.write(runDate)
        myLog.write(headers)
        for item in zip(list1, list2):
            myLog.write(colWdth.format(*item))


# ################# #
#       MAIN        #
# ################# #

def main():
    print 'Processing geodatabase...'
    workspace = arcpy.env.workspace = r'C:\Scripts\Redefine_Projection\Thomas\2016-01-25_GeoDB03_gd_Export.gdb'

    toRedefine = 'ETRS_1989_UTM_Zone_32N_6stellen'
    defineProjection(workspace, toRedefine)
    datasets = recursiveDatasets(workspace)
    print 'Logging results...'
    # list of projections
    projections = []
    for dataset in datasets:
        desc = arcpy.Describe(dataset)
        projections.append(desc.spatialReference.Name)
    # logging
    myLog = r"C:\Scripts\Redefine_Projection\Log\RedefineProjection.log"
    today = date.today()
    runDate = 'Tag der Durchführung: ' + today.strftime("%Y.%m.%d") + '\n'
    # first column header is 'Feature Class' justified left w/125 character buffer before 'Neue Spatial Reference' header
    headers = '{0: <125}'.format('Pfad der Datensatz') + 'Spatial Reference' + '\n'
    colWdth ="{:<125}"*2 + "\n"   # 2 columns with 125 character width
    Logging(myLog, 'a', runDate, headers, datasets, projections, colWdth)


if __name__ == '__main__':
    main()

MarcoDellenbach

I have the same problem. The dataset and feature classes seem to be changed, but the desc.spatialReference.name ist still named as the old spatial reference.

After copying the dataset in a new geodatabase, the desc.spatialReference.name ist correct and consistent.

Is there a solution/workround (without copying)?

AndrewLowerre

Hi Darren,

This was my understanding as well, but since Trillium seemed to have found something that worked, I figured case closed.

Cheers,

Andrew

DarrenWiens2

Just a note about Andrew Lowerre's suggestion for Define Projection. The general wisdom is that you shouldn't use Define once a CRS has been defined, because you have correctly defined the CRS in the first place. In this case, you have "incorrectly" (on purpose) defined your CRS with the "wrong" name. It is perfectly reasonable to use Define to change the name. I suspect your script mirrors the Define tool - it would be interesting to see the run time comparison.

TrilliumLevine1

Hi Andrew,

Thanks for the response, but that won't work since (as far as I know) you can't define a projection for something that already has one defined. Anyway, I figured out how to do it in code:

import os
import arcpy

workspace = r"C:\Scripts\Reproject"
newProjection = "PROJCS['ETRS_1989_UTM_Zone_32N'"

def recursiveProjections(workspace):
    """
    Function iterates through a workspace and its subfolders using arcpy.da.walk and returns
    a list of spatial reference objects of all geographic datasets (including those inside
    geodatabases).  Parameter: target workspace

    """
    projections = []
    for dirpath, dirnames, filenames in arcpy.da.Walk(workspace):
        for filename in filenames:
            desc = arcpy.Describe(os.path.join(dirpath, filename))
            srObject = desc.spatialReference
            projections.append(srObject)
    return projections

def editProjection(workspace):
    projections = recursiveProjections(workspace)
    for projection in projections:
        projectionParameters = projection.exportToString()
        parameterSplit = projectionParameters.split(",")
##        print parameterSplit[0]
        parameterSplit[0] = newProjection
        SR_outstring = ",".join(parameterSplit)
        print SR_outstring

editProjection(workspace)

AndrewLowerre

Hi Trillium,

Perhaps the 'Define Projection' tool (ArcGIS Help (10.2, 10.2.1, and 10.2.2) ) is what you're after?

Hope this helps,

Andrew

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