Using the Spatial Statistics Data Object (SSDataObject) Makes Feature IO Simple

SSDataObject does the read/write and accounting of feature/attribute and NumPy Array order
Write/Utilize methods that take NumPy Arrays

Using NumPy as the common denominator

Could use the ArcPy Data Access Module directly, but there are host of issues/information one must take into account:
- How to deal with projections and other environment settings?
- How Cursors affect the accounting of features?
- How to deal with bad records/bad data and error handling?
- How to honor/account for full field object control?
- How do I create output features that correspond to my inputs?
  - Points are easy, what about Polygons and Polylines?
Spatial Statistics Data Object (SSDataObject)
- Almost 30 Spatial Statistics Tools written in Python that ${\bf{must}}$ behave like traditional GP Tools
- Use SSDataObject and your code should adhere

The Data Analysis Python Modules

Basic Imports



In [15]:

    
import arcpy as ARCPY
import numpy as NUM
import SSDataObject as SSDO

Initialize and Load Fields into Spatial Statsitics Data Object

The Unique ID Field ("MYID" in this example) will keep track of the order of your features
- You can use ssdo.oidName as your Unique ID Field
- You have no control over Object ID Fields. It is quick, assures "uniqueness", but can't assume they will not get "scrambled" during copies.
- To assure full control I advocate the "Add Field (LONG)" --> "Calculate Field (From Object ID)" workflow.



In [16]:

    
inputFC = r'../data/CA_Polygons.shp'
ssdo = SSDO.SSDataObject(inputFC)
ssdo.obtainData("MYID", ['GROWTH', 'LOGPCR69', 'PERCNOHS', 'POP1969'])
df = ssdo.getDataFrame()
print(df.head())









    



       GROWTH  LOGPCR69  PERCNOHS  POP1969
158  0.011426  0.176233      37.0  1060099
159 -0.137376  0.214186      38.3      398
160 -0.188417  0.067722      41.4    11240
161 -0.085070 -0.118248      42.9   101057
162 -0.049022 -0.081377      48.1    13328

You can get your data using the core NumPy Arrays

Use .data to get the native data type
Use the returnDouble() function to cast explicitly to float



In [17]:

    
pop69 = ssdo.fields['POP1969']
nativePop69 = pop69.data
floatPop69 = pop69.returnDouble()
print(floatPop69[0:5])









    



[  1.06009900e+06   3.98000000e+02   1.12400000e+04   1.01057000e+05
   1.33280000e+04]

You can get your data in a PANDAS Data Frame

Note the Unique ID Field is used as the Index



In [18]:

    
df = ssdo.getDataFrame()
print(df.head())









    



       GROWTH  LOGPCR69  PERCNOHS  POP1969
158  0.011426  0.176233      37.0  1060099
159 -0.137376  0.214186      38.3      398
160 -0.188417  0.067722      41.4    11240
161 -0.085070 -0.118248      42.9   101057
162 -0.049022 -0.081377      48.1    13328

By default the SSDataObject only stores the centroids of the features



In [19]:

    
df['XCoords'] = ssdo.xyCoords[:,0]
df['YCoords'] = ssdo.xyCoords[:,1]
print(df.head())









    



       GROWTH  LOGPCR69  PERCNOHS  POP1969       XCoords       YCoords
158  0.011426  0.176233      37.0  1060099 -1.356736e+07  4.503012e+06
159 -0.137376  0.214186      38.3      398 -1.333797e+07  4.637142e+06
160 -0.188417  0.067722      41.4    11240 -1.343007e+07  4.615529e+06
161 -0.085070 -0.118248      42.9   101057 -1.353566e+07  4.789809e+06
162 -0.049022 -0.081377      48.1    13328 -1.341895e+07  4.581597e+06

You can get the core ArcPy Geometries if desired

Set requireGeometry = True



In [20]:

    
ssdo = SSDO.SSDataObject(inputFC)
ssdo.obtainData("MYID", ['GROWTH', 'LOGPCR69', 'PERCNOHS', 'POP1969'],
               requireGeometry = True)
df = ssdo.getDataFrame()
shapes = NUM.array(ssdo.shapes, dtype = object)
df['shapes'] = shapes
print(df.head())









    



       GROWTH  LOGPCR69  PERCNOHS  POP1969  \
158  0.011426  0.176233      37.0  1060099   
159 -0.137376  0.214186      38.3      398   
160 -0.188417  0.067722      41.4    11240   
161 -0.085070 -0.118248      42.9   101057   
162 -0.049022 -0.081377      48.1    13328   

                                                shapes  
158  (<geoprocessing array object object at 0x00000...  
159  (<geoprocessing array object object at 0x00000...  
160  (<geoprocessing array object object at 0x00000...  
161  (<geoprocessing array object object at 0x00000...  
162  (<geoprocessing array object object at 0x00000...

Coming Soon... ArcPy Geometry Data Frame Integration

In conjunction with the ArcGIS Python SDK
Spatial operators on ArcGIS Data Frames: selection, clip, intersection etc.

Creating Output Feature Classes

Simple Example: Adding a field of random standard normal values to your input/output
appendFields can be used to copy over any fields from the input whether you read them into the SSDataObject or not.
E.g. 'NEW_NAME' was never read into Python but it will be copied to the output. This can save you a lot of memory.



In [21]:

    
import numpy.random as RAND
import os as OS
ARCPY.env.overwriteOutput = True
outArray = RAND.normal(0,1, (ssdo.numObs,))
outDict = {}
outField = SSDO.CandidateField('STDNORM', 'DOUBLE', outArray, alias = 'Standard Normal')
outDict[outField.name] = outField
outputFC = OS.path.abspath(r'../data/testMyOutput.shp')
ssdo.output2NewFC(outputFC, outDict, appendFields = ['GROWTH', 'PERCNOHS', 'NEW_NAME'])



In [ ]: