[GIS] How to use ArcPy to list feature class and number of rows per feature class

arcgis-10.0arcpy

I would like to iterate a geodatabse to get the name of each feature class/data set in it, in addition to the number of rows in the feature class. I would also like to identify whether the dataset that is being printed is a feature class or feature dataset.

The code that I have now prints each feature class and feature data set; but does not denote whether if the object printed is a feature class or feature data set. How would I print the number of rows per feature class in addition to denote whether if it is a feature class or feature dataset?

I am using ArcGIS Desktop 10.0 and a direct connect via spatial database.

import arcpy   
arcpy.env.workspace='myworkspace'

    datasetList = arcpy.ListDatasets("*", "Feature")
    for dataset in datasetList:
        print dataset
        fcList = arcpy.ListFeatureClasses("*","",dataset)
        fcList.sort()
        for fc in fcList:
            print fc
        for fc in fcList:
            arcpy.GetCount_management(fc)

Sample Output:

SDEDEV.SDE.Boundaries
SDEDEV.SDE.CTYA_GLEN
SDEDEV.SDE.ZipCode
SDEDEV.SDE.Streets
SDEDEV.SDE.CAMS_Streets_2012
SDEDEV.SDE.ROW
SDEDEV.SDE.Streets_COG

Best Answer

The docs for GetCount don't say it very well but it returns a gp result object and not a number.. to get a number (see example 2) you need to use getOutput(0) and int.

Your script (modified):

import arcpy   
arcpy.env.workspace='myworkspace'

    datasetList = arcpy.ListDatasets("*", "Feature")
    for dataset in datasetList:
        print dataset
        fcList = arcpy.ListFeatureClasses("*","",dataset)
        fcList.sort()
        for fc in fcList:
            cnt = int(arcpy.GetCount_management(fc).getOutput(0))
            print "{0} {1}".format(fc,cnt) # print in the format "fcname count"

Related Solutions

[GIS] Deleting feature class features faster using ArcPy

Which part of the script is actually taking up most of the time? There are about 5 other steps going on before you actually start deleting stuff.

You might want to break your script down into bite-sized tests. For example, instead of creating a temporary connection file, listing a bunch of datasets, listing their contents, counting their records, and then finally actually doing what you want to do (deleting features), just pass in a single feature class with a premade connection file to DeleteFeatures and see how long that takes.

If that performs acceptably then create another test to time the next potential trouble spot: counting rows. And another for listing feature classes within a feature dataset, and yet another for listing feature datasets within a geodatabase.

If, on the other hand, DeleteFeatures does not perform acceptably, then at least we know where the problem is. In that case I would be more inclined to look at how your geodatabase is designed:

Are any of your feature datasets versioned? When using versioning there exists an additional pair of A (adds) and D (deletes) tables for each versioned table, and when you delete features you aren't deleting records in the base table, you are adding records to the D table. This will take much longer than if it was not versioned.
Since your feature classes all seem to be in feature datasets, do they participate in geodatabase behavior such as a topology or geometric network? When you add/remove/modify features participating in geodatabase behavior there is a lot more overhead.
Also note that contrary to popular belief, feature datasets are not designed to be used as an organizational tool:

Feature data sets exist in the geodatabase to define a scope for a spatial reference. All feature classes that participate in topological relationships with one another (e.g., a geometric network) must have the same spatial reference. Feature data sets are a way to group feature classes with the same spatial reference so that they can participate in topological relationships with each other.

To most users, feature data sets also have a natural organizational quality, much like a folder on a file system. Since for many GIS applications the majority of the data has the same spatial reference, the temptation to group large numbers of feature classes into feature data sets is irresistible.

Feature data sets, however, are not free. When you open a feature class contained in a feature data set to look at its properties or draw or query it in ArcCatalog™, ArcMap™, or a custom application, all of the other feature classes in that feature data set are also opened. This is done because updates to a feature class in a feature data set can potentially ripple to other feature classes in the feature data set that participate in topological relationships.

From: Multiuser Geographic Information Systems with ArcInfo 8 (April 2000)

So that might be another source of overhead even if they do not participate in a topology or geometric network.

Beyond the arcpy DeleteFeatures/DeleteRows commands:

If you have SDE administration command access you could use:

sdetable -o truncate -t <tablename>

This issues truncate table commands to your DBMS so it should be much faster, but note that this ignores geodatabase behavior.
Using ArcSDESQLExecute to issue TRUNCATE TABLE commands directly (again bypassing geodatabase behavior), but this is very trouble-prone as you would need to issue one for each table that makes up a feature class (base, F, S, I, A, D, etc.) Failing to do this carefully and correctly could leave your data in an inconsistent state.

Arcpy – How to Count Feature Classes in Geodatabase

The arcpy.da.Walk() method is the way to go:

import arcpy, os

workspace = r"C:\Users\OWNER\Documents\ArcGIS\Default.gdb"
feature_classes = []
for dirpath, dirnames, filenames in arcpy.da.Walk(workspace,
                                                  datatype="FeatureClass",
                                                  type="Any"):
    for filename in filenames:
        feature_classes.append(os.path.join(dirpath, filename))

print "There are %s featureclasses in the workspace" % len(feature_classes)

The main operators here are arcpy.da.Walk and len(). arcpy.da.Walk simply walks through folders and subfolders and collects files of datatype="FeatureClass" using feature_classes.append(os.path.join(dirpath, filename)). Finally, len() is used to count the number of files in the feature_classes = [] list.

EDIT:

From a benchmark standpoint and in the interest of science, it appears that arcpy.da.Walk method is significantly faster than the other approach. I tested them on a FGDB with 7 FDS and 35 FC's. Here are the results:

import arcpy, os, time

###########################################################################
# METHOD 1
start = time.clock()
workspace = r"C:\Users\OWNER\Documents\ArcGIS\Default.gdb"
feature_classes = []
for dirpath, dirnames, filenames in arcpy.da.Walk(workspace, datatype="FeatureClass", type="Any"):
    for filename in filenames:
        feature_classes.append(os.path.join(dirpath, filename))

print "There are %s featureclasses in the workspace" % len(feature_classes)

end = time.clock()
method1 = (end - start)

############################################################################
# Method 2
start = time.clock()
arcpy.env.workspace = r"C:\Users\OWNER\Documents\ArcGIS\Default.gdb"

# Get stand alone FCs
fccount = len(arcpy.ListFeatureClasses("",""))

# Get list of Feature Datasets and loop through them
fds = arcpy.ListDatasets("","")
for fd in fds:
    oldws = arcpy.env.workspace
    arcpy.env.workspace = oldws + "\\" + fd
    fccount = fccount + len(arcpy.ListFeatureClasses("",""))
    arcpy.env.workspace = oldws

print fccount

end = time.clock()
method2 = (end - start)
##########################################################################

print 'method1 completed in %s seconds; method2 completed in %s seconds' % (method1, method2)

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Best Answer

Related Solutions

[GIS] Deleting feature class features faster using ArcPy

Arcpy – How to Count Feature Classes in Geodatabase

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