Quick & Dirty Arcpy: Verify a Coded Value Domain Code

I’ve been working on a few different data import routines and one of the things I recently built was the ability to verify that a potential Code to be entered into a field with a Coded Value Domain is valid.

The logic of the code is pretty straight-forward. Get a field’s domain and check that a potential value is one of the code values. The biggest “trick” in this code is that arcpy.da.ListDomains, which locates a field’s domain, takes a geodatabase (or Enterprise geodatabase connection file) as its only parameter. The documentation says it takes a workspace, but it does not like a feature dataset, which a feature class might be in.

A couple caveats about the code. It only returns True if a field exists, has a coded value domain, and the value tested is one of the (case-sensitive) valid codes. While I have an ArcToolbox tool to call it for illustration purposes, I’m only calling it from code so I wanted tight requirements.

Anyhow, here is the code or download it from GitHub.

import arcpy

inFeatureClass = sys.argv[1]
inField = sys.argv[2]
inValue = sys.argv[3]

# getFeatureClassParentWorkspace: This script gets the geodatabase for a
# feature class. The trick here is that feature classes can be within a
# feature dataset so you need to account for two possible levels in the
# directory structure.
def getFeatureClassParentWorkspace(inFeatureClass):
    describeFC = arcpy.Describe(inFeatureClass)
    if (describeFC.dataType == 'FeatureClass') or (describeFC.dataType == 'Table'):
        workspace1 = describeFC.path
        describeWorkspace1 = arcpy.Describe(workspace1)
        if (describeWorkspace1.dataType == 'FeatureDataset'):
            return describeWorkspace1.path
        return workspace1

    return None

# Find a field within a feature class
def getField(inFeatureClass, inFieldName):
  fieldList = arcpy.ListFields(inFeatureClass)
  for iField in fieldList:
    if iField.name.lower() == inFieldName.lower():
      return iField
  return None

#Get a field's domain
def getDomain(inFeatureClass, inField):
    theField = getField(inFeatureClass,inField)
    if (theField <> None):
        searchDomainName = theField.domain
        if (searchDomainName <> ""):
            for iDomain in arcpy.da.ListDomains(getFeatureClassParentWorkspace(inFeatureClass)):
                if iDomain.name == searchDomainName:
                    return iDomain
    return None

#Get the domain.
def validDomainValue(inFeatureClass,inField,inValue):
    theDomain = getDomain(inFeatureClass,inField)

    if not (theDomain is None):
        if (theDomain.domainType == "CodedValue"):
            if theDomain.codedValues.has_key(inValue):
                return True
    return False

if (validDomainValue(inFeatureClass,inField,inValue)):
    arcpy.AddMessage("Value ({0}) is valid for field [{1}].".format(inValue,inField))
    arcpy.AddError("ERROR: Value ({0}) is invalid for field [{1}].".format(inValue,inField))

Quick & Dirty ArcPy: Listing Data Sources

I just had the need to go through a directory containing many (100+) layer files (.lyr) and verify the data sources in each. I could have loaded each into ArcMap and checked the properties, but choose not to. Here’s the bare-bones script I used instead:

import arcpy, glob,os

theDir = r"L:\gdrs\data\org\us_mn_state_dnr\elev_minnesota_lidar\\"

for iFile in glob.glob("*.lyr"):
    print iFile
    lyr = arcpy.mapping.Layer(iFile)
    for i in arcpy.mapping.ListLayers(lyr):
            print "    {0}: {1}".format(i,i.dataSource)
            print "    {0}: Does not support dataSource".format(i)

print "Done!"

Quick & Dirty arcpy: Compare Feature Class Table Schemas

I’m in the process of rewriting a process, moving most of the processing from arcpy to postgresql-enabled python (love me some psycopg2).

One of the QC checks I’m doing at the end of this re-write is just verifying that the feature class schemas are the same (or that the differences are intended)  under the new process as they were in the old process.

And while ArcGIS does have a good tool for this, there were a couple tweaks I wanted to make. Most notably, I wanted a list of fields that are not in both feature classes.

ArcGIS Table Compare

So I made a quick & dirty script to do that, nothing especially clever but I’ve found it useful. Download it from GitHub. I have it currently set up to work on feature layers but you should be able to change the toolbox parameter types to allow feature classes or tables.

import arcpy,sys,os

def printit(inMessage):
    print inMessage

featureclass1 = sys.argv[1]
featureclass2 = sys.argv[2]

tableheaders = 'name, type, width, precision, domain'

def makeFieldDict(inFC):
    d = arcpy.Describe(inFC)
    printit("Dataset: "+d.baseName)
    printit("Type: "+d.dataType)
    printit("Path: "+d.catalogPath)
    printit(" ")


    printit (tableheaders)
    fieldDict = dict()
    printit (lFields)
    for lf in lFields:
        fieldDict[lf.name] = [lf.name,lf.type,lf.length,lf.precision,lf.domain]
        printit (lf.name+", "+lf.type +", "+str(lf.length)+", "+str(lf.precision)+", "+lf.domain)
    return fieldDict

fieldDict1 = makeFieldDict(featureclass1)
fieldDict2 = makeFieldDict(featureclass2)
errorList = []
printit(" ")
printit(" ")
printit("Comparing Fields:")
for iField in sorted(list(set(fieldDict1.keys()+fieldDict2.keys()))):
    if not (fieldDict1.has_key(iField)):
        theResult = " {0} not found in {1}".format(iField,featureclass1)
    elif not (fieldDict2.has_key(iField)):
        theResult = " {0} not found in {1}".format(iField,featureclass2)
        if (fieldDict1[iField] == fieldDict2[iField]):
            theResult = " {0} OK".format(iField)
            theResult = " {0} Have Different Definitions \n   {1}: {2}\n   {3}: {4}".format(iField,featureclass1,fieldDict1[iField],featureclass2,fieldDict2[iField])

    printit( theResult )

printit(" ")
printit(" ")
if len(errorList) == 0:
    printit("GOOD! No difference Found!")
    printit("These Differences Found:")
    for iError in errorList:


Quick & Dirty arcpy: Bulk Changing Field Values

In mapping cross sections, our geologists often find themselves renaming their stratigraphic units midway, or at the end, of creating multiple cross sections.  This can cause a situation where we need to change multiple values in multiple fields in multiple feature classes–a situation that can get messy very fast.

Perfect situation for a quick & dirty arcpy script and, in this case, an ArcToolbox tool that can be downloaded.

This tool will change all feature classes in the O:\clay_cga\sand-distribution_model\dnrPackages\stratlines directory.

It will look at two fields, [strat] and [unit] and make these changes:

  • “go” becomes “gro”
  • “goc” becomes “grc”
  • “sgb” becomes “grb”

And since I have Case Sensitive checked, “Go” will not get changed to “gro”.  Also note that only full values that match values in the Old Value List get changed, part matches are left as-is so “got” would be left as-is even though the first two characters match “go”.


Bulk Field Change

import arcpy
import sys, string, arcgisscripting
import arcpy

def printit(inString):
    print inString

def printerr(inString):
    print inString

def fieldExists(tablename,indexname):

 if not arcpy.Exists(tablename):
  return False

 tabledescription = arcpy.Describe(tablename)

 for iField in tabledescription.fields:
     if (iField.Name.lower() == indexname.lower()):
         return True

 return False

if len(sys.argv) > 1:
    inDirectory = sys.argv[1]
    inFieldNameRaw = sys.argv[2]
    oldValue = sys.argv[3].replace(","," ")
    newValue = sys.argv[4].replace(","," ")
    caseSensitiveRaw = sys.argv[5]
    inDirectory = r"C:\temp\test\stratest"
    inFieldNameRaw = "strat"
    oldValue = "go, goc, sgb".replace(","," ")
    newValue = "gro grc grb".replace(","," ")
    caseSensitiveRaw = "true"

caseSensitive = (caseSensitiveRaw.lower() == "true")
fieldNameList = inFieldNameRaw.replace(","," ").split()

printit(" Workspace: "+str(inDirectory))
printit( " inFieldName: "+str(inFieldNameRaw))
printit( " oldValue: "+str(oldValue))
printit( " newValue: "+str(newValue))
printit( " caseSensitive: "+str(caseSensitive))

valueDict = dict()

def initialQC():
    global valueDict

    if not (arcpy.Exists(inDirectory)):
        printerr("Workspace {0} does not exist".format(inDirectory))
        return False

    if (len(oldValue.split()) <> len(newValue.split())):
        printerr("Number of values in {0} does not equal number of values in {1}".format(oldValue,newValue))
        return False

    iValueIndex = 0
    for iOldValue in oldValue.split():
        if (caseSensitive):
            thisKey = iOldValue
            thisKey = iOldValue.lower()

        if (valueDict.has_key(thisKey)):
            printerr("ERROR: Value, {0}, is repeated, cancelling...".format(thisKey))
            return False

        valueDict[thisKey] = newValue.split()[iValueIndex]
    return True

def makeFieldList(inFC):
    thisFieldList = []

    for iField in fieldNameList:
        if (fieldExists(inFC,iField)):

    return thisFieldList

def main():
    arcpy.env.workspace = inDirectory
    for iFC in arcpy.ListFeatureClasses():
        printit("Working on {0}".format(iFC))

        iFieldList = makeFieldList(iFC)
        if (len(iFieldList) == 0):
            printit(" No fields to change, Skipping...")

        rows = arcpy.UpdateCursor(iFC)

        changes = 0
        printit(" Changing Rows")
        for row in rows:
            iChange = 0
            for iField in iFieldList:
                iValue = str(row.getValue(iField))
                newValue = iValue

                if valueDict.has_key(iValue):
                    newValue = valueDict[iValue]
                    if not (caseSensitive):
                        if valueDict.has_key(iValue.lower()):
                            newValue = valueDict[iValue.lower()]

                if (newValue <> iValue):
                    printit("CHANGE {0}".format(newValue))

            if (iChange > 0):
        printit(" Made {0} changes".format(changes))
        del row
        del rows


if (initialQC()==True):


Quick & Dirty python: Converting a text file to audio (.wav)

This is a bit of a tangent but for some crazy reason, I wanted to convert some text to audio so I could listen to it while I drive. A quick Google search left me without any freeware that could handle the 53 page document–there are some cool websites that do text to mp3 like vozme and YAKiToMe! but they didn’t convert the whole document. I then found pyTTS, a python package that serves as a wrapper to the Microsoft Speech API (SAPI) , which has been in version 5 since 2000. But I didn’t easily find a version of pyTTS for python 2.6. So I decided to see if I could roll my own.

As it turns out, getting python to talk using SAPI is relatively easy. Reading a plain text file can be done in a few lines.

from comtypes.client import CreateObject

infile = "c:/temp/text.txt"

engine = CreateObject("SAPI.SpVoice")

f = open(infile, 'r')
theText = f.read()


And it wasn’t that much more to have it write out a .wav file:

from comtypes.client import CreateObject

engine = CreateObject("SAPI.SpVoice")
stream = CreateObject("SAPI.SpFileStream")

infile = "c:/temp/text.txt"
outfile = "c:/temp/text4.wav"
stream.Open(outfile, SpeechLib.SSFMCreateForWrite)
engine.AudioOutputStream = stream

f = open(infile, 'r')
theText = f.read()



And with that chunk of code, I was able to convert my 54 page document into a 4 hour long .wav file (over 600 MB) that I used another software package to convert to .mp3 (200 MB). The voice is a bit robotic but not too bad, I just hope the content that I converted (a database specification standard) doesn’t put me to sleep while I drive.

Quick & Dirty arcpy: Autopan ArcMap using arcpy

Question: How do I get ArcMap to automatically pan through an area.

As I mentioned in a previous post, I recently had the need to have ArcMap automatically pan through a project area. My first attempt was to print a series of data-driven pages (using a fishnet polygon layer as the index) this but that did not accomplish what I needed so I switched to arcpy, which made the task simple enough. Nothing special or tricky about this code, but just did not find it anywhere else.

The one thing to note is that I have a 1 second pause between pans–this was to allow image tiles to download. You will need to adjust the delay to meet your needs. The toolbox and code can also be downloaded.

import sys,arcpy,datetime
inLayer = sys.argv[1]

def printit(inMessage):
    print inMessage

mxd = arcpy.mapping.MapDocument("CURRENT")

arcpy.MakeFeatureLayer_management(inLayer, "indexLayer")

df = arcpy.mapping.ListDataFrames(mxd)[0]
newExtent = df.extent

iCount = 0
iTotal = (arcpy.GetCount_management("indexLayer").getOutput(0))

for row in cur:
    thisPoly = row.getValue("Shape")
    newExtent.XMin, newExtent.YMin = thisPoly.extent.XMin, thisPoly.extent.YMin
    newExtent.XMax, newExtent.YMax = thisPoly.extent.XMax, thisPoly.extent.YMax
    df.extent = newExtent
    printit("Panned to feature {0} of {1}".format(iCount,iTotal))

del row
del cur

Quicker & Cleaner python recursive folder search

As contributor of the day, Jason Scheirer, pointed out, python has a simple, direct way to browse through the subdirectories of a directory–os.walk

Here is a bare-bones example of using it to print out the subdirectories in a path. The files variable of the 3-tuple is a list of files similar to the dirs variable that I loop through.

Thanks Jason for pointing out something I missed.

import os

theDir = 'c:/temp/'

for root, dirs, files in os.walk(theDir,True,None):
    for idir in dirs:
        print "     directory:   {0}/{1}".format(root,idir)

Quick & Dirty python recursive folder search

Someone asked how to have python recursively search a folder structure. There may be a better way but this is how I typically do it–it basically starts with one directory and loops through the contents compiling a list of sub-directories as it goes through the contents.


import glob, os

theDir = 'c:/temp/'
theDirList = []

while len(theDirList) > 0:
    newDirList = []
    for iDir in theDirList:
        print iDir
        for iFile in glob.glob(iDir+"/*"):
            if (os.path.isdir(iFile)):

    theDirList = newDirList

Quick & Dirty arcpy: Batch Splitting Polylines to a Specific Length.

For some odd reason, I wanted to split all the arcs in a polyline feature class to a specific length–if a specific feature was longer than the target length, it would become two or more separate polyline records.

Here is the bare-bones script that copies an existing feature class into a new feature class then processes each record, splitting it into multiple records if the polyline is longer than the user-specified tolerance.  Some cautionary notes:

  • This is Quick & Dirty code–minimal error catching or documentation.
  • I basically tested this against one feature class (the one I wanted to split) once I got it to work, I quit.
  • There is some rounding error–features may be a tad bit off (a few ten-thousandths of a unit).
  • I did not test against multi-part features.
  • The tolerance is the native units of the data–if your data is in meters but you want to split the polylines every mile, enter 1,609.344.

I have included both a toolbox file (.tbx) and python script (.py).  After loading the toolbox, you’ll have to change the Source of the script by right-clicking on it, selecting the Source tab, and then navigating to the .py file.

Here is the code for the Googlebots, but you are better off just downloading it.

import arcpy
import sys, math

def printit(inMessage):
    print inMessage

if len(sys.argv) > 1:
    inFC = sys.argv[1]
    outFC = sys.argv[2]
    alongDistin = sys.argv[3]
    alongDist = float(alongDistin)
    inFC = "C:/temp/asdfasdf.mdb/jkl"
    OutDir = "C:/temp/asdfasdf.mdb"
    outFCName = "jkl2d"
    outFC = OutDir+"/"+outFCName
    alongDist = 1000

if (arcpy.Exists(inFC)):
    print(inFC+" does exist")
    print("Cancelling, "+inFC+" does not exist")

def distPoint(p1, p2):
    calc1 = p1.X - p2.X
    calc2 = p1.Y - p2.Y

    return math.sqrt((calc1**2)+(calc2**2))

def midpoint(prevpoint,nextpoint,targetDist,totalDist):
    newX = prevpoint.X + ((nextpoint.X - prevpoint.X) * (targetDist/totalDist))
    newY = prevpoint.Y + ((nextpoint.Y - prevpoint.Y) * (targetDist/totalDist))
    return arcpy.Point(newX, newY)

def splitShape(feat,splitDist):
    # Count the number of points in the current multipart feature
    partcount = feat.partCount
    partnum = 0
    # Enter while loop for each part in the feature (if a singlepart feature
    # this will occur only once)
    lineArray = arcpy.Array()

    while partnum < partcount:
        # Print the part number
        #print "Part " + str(partnum) + ":"
        part = feat.getPart(partnum)
        #print part.count

        totalDist = 0

        pnt = part.next()
        pntcount = 0

        prevpoint = None
        shapelist = []

        # Enter while loop for each vertex
        while pnt:

            if not (prevpoint is None):
                thisDist = distPoint(prevpoint,pnt)
                maxAdditionalDist = splitDist - totalDist

                print thisDist, totalDist, maxAdditionalDist

                if (totalDist+thisDist)> splitDist:
                    while(totalDist+thisDist) > splitDist:
                        maxAdditionalDist = splitDist - totalDist
                        #print thisDist, totalDist, maxAdditionalDist
                        newpoint = midpoint(prevpoint,pnt,maxAdditionalDist,thisDist)

                        lineArray = arcpy.Array()
                        prevpoint = newpoint
                        thisDist = distPoint(prevpoint,pnt)
                        totalDist = 0

                totalDist = 0

            prevpoint = pnt                
            pntcount += 1

            pnt = part.next()

            # If pnt is null, either the part is finished or there is an
            #   interior ring
            if not pnt:
                pnt = part.next()
                if pnt:
                    print "Interior Ring:"
        partnum += 1

    if (lineArray.count > 1):

    return shapelist

if arcpy.Exists(outFC):


#origDesc = arcpy.Describe(inFC)
#sR = origDesc.spatialReference

#revDesc = arcpy.Describe(outFC)

deleterows = arcpy.UpdateCursor(outFC)
for iDRow in deleterows:       

del iDRow
del deleterows

inputRows = arcpy.SearchCursor(inFC)
outputRows = arcpy.InsertCursor(outFC)
fields = arcpy.ListFields(inFC)

numRecords = int(arcpy.GetCount_management(inFC).getOutput(0))
OnePercentThreshold = numRecords // 100


iCounter = 0
iCounter2 = 0

for iInRow in inputRows:
    inGeom = iInRow.shape
    if (iCounter2 > (OnePercentThreshold+0)):
        printit("Processing Record "+str(iCounter) + " of "+ str(numRecords))

    if (inGeom.length > alongDist):
        shapeList = splitShape(iInRow.shape,alongDist)

        for itmp in shapeList:
            newRow = outputRows.newRow()
            for ifield in fields:
                if (ifield.editable):
            newRow.shape = itmp

del inputRows
del outputRows


Quick & Dirty arcpy: Field Listings

I have to often get a table structure for a feature class or table into either a spreadsheet or word processing document.  There might be an easy way to do this in ArcGIS 10 but I haven’t found it.  So, as is my nature, I decided to roll my own.

This is a bare-bones script that iterates through the fields, printing the field name, type, width, and precision.  There are three optional features to it:

  • You can choose to have it list the domain, if there is one, on each field.
  • You can have it write to a text file (otherwise you can just copy & paste the results from the results window).
  • You can have it count the number of populated records.  This can take a long time if working with a large dataset.  Also note that my logic for determining what constitutes being populated may not be what you need but the structure is there.  I also do not account for all field types, if the field is of a type I have not account for, the code will return -999.

To use the script from ArcToolbox, you need to pass it four parameters, their Names, type, whether they are input or output, and whether they are required or optional are:

  • featureclass, Table, Input, Required
  • includedomainstring, Boolean, Input, Required (controls whether or not domains are exported)
  • doCountsRespone, Boolean, Input, Required (controls whether or not you want to get the number of populated records.  (Your definition of populated may vary from my code)
  • outputFile, File, Output, Optional (optional output file to write)

Here is the code, but you are better off just downloading it since I haven’t figured out a good way to have WordPress play nicely with python’s indenting.

# Name: ListFields-arcpy.py
# Purpose: Lists the fields, their type, width, and precision
# Can either have it export it to a CSV file or copy
# and paste from the results window.
# To use, create a tool from the script and add 3 parameters:
#  1) Table, Input, Required
#  2) Boolean, Input, Required (controls whether or not domains are exported)
#  3) Boolean, Input, Rekquired (controls whether or not you want to get the number of
#  Populated records.&nbsp; (Your defintion of populated may vary from my code)
#  4) File, Output, Optional (optional output file to write)

import arcpy,sys,os

def printit(inMessage):
 print inMessage

if len(sys.argv) > 4:
 featureclass = sys.argv[1]
 includedomainstring = sys.argv[2]
 doCountsRespone = sys.argv[3]
 outputFile = sys.argv[4]
 featureclass = "C:/temp/before.shp"
 includedomainstring = "false"
 doCountsRespone = "true"
 outputFile = "C:/temp/before.csv"

if (outputFile == ""):
 doOutputFile = False
 doOutputFile = True

if (str(doCountsRespone).lower() == "true"):
 doCounts = True
 doCounts = False

if (str(includedomainstring).lower() == "true"):
 includedomain = True
 includedomain = False


d = arcpy.Describe(featureclass)
printit("Dataset: "+d.baseName)
printit("Type: "+d.dataType)
printit("Path: "+d.catalogPath)
printit(" ")

tableheaders = 'name,type,width,precision'

if (doCounts == True):

if (includedomain == True):

if (doOutputFile):
 tmpfile = open(outputFile,"w")

printit (tableheaders)
for lf in lfields:

 pThisline = lf.name+","+lf.type +","+str(lf.length)+","+str(lf.precision)

 if (doCounts == True):

 rowCount = 0

 #Note that I do not account for all field types
 #Also note that my definition of being populated may vary from yours.
 #I am using -999 as a flag to indicate a field type was not successfully
 if (lf.type == "Double") or (lf.type == "Single")&nbsp; or (lf.type == "Integer") or (lf.type == "SmallInteger"):
  queryString = '"'+lf.name + '" > 0'
  rows = arcpy.SearchCursor(featureclass, queryString, "", "", "")
 elif (lf.type == "String"):
  queryString = '"'+lf.name + '" <> ' + "''"
  rows = arcpy.SearchCursor(featureclass, queryString, "", "", "")
  rowCount = -999
  #rows = arcpy.SearchCursor(featureclass, "", "", "", "")

 if (rowCount == 0):
  for row in rows:


 if (includedomain == True):

 printit (pThisline)

 if (doOutputFile):

if (doOutputFile):