Python presentation by Thomas Mackey at the Melbourne Esri Australia Developer Meetup

1. Python in 10.1
Thom Mackey

2. Contents
• arcpy Enhancements
• Add-ins
• Python Toolboxes

3. FeatureClassToNumPyArray
import arcpy
import numpy
input = "C:/Data/ABSData.gdb/VIC_CCDs"
arr = arcpy.da.FeatureClassToNumPyArray(input,('CCD', 'pop_m', 'pop_f'))
# Sum the total population for males & females #
print(arr['pop_m'].sum())
print(arr['pop_f'].sum())
# Sum the female population for a particular CCD #
print(arr[arr['CCD'] == "2010101"]['pop_f'].sum())

4. FeatureClassToNumPyArray
import arcpy
import numpy
input = "C:/Data/ABSData.gdb/VIC_CCDs"
field1 = "INCOME"
field2 = "EDUCATION"
arr = arcpy.da.FeatureClassToNumPyArray(input, (field1, field2))
# Print correlation coefficients for the two fields
print(numpy.corrcoef((arr[field1],arr[field2])))

5. Improved Cursors
# Turn the contents of a GDB table into a Python list of lists
# Simple syntax & little code
with arcpy.da.SearchCursor(zonalstats_results_table,
["MINORITY","MAJORITY","MEAN"]) as tblcur:
results = [r for r in tblcur]

6. Improved Cursors
import arcpy
arcpy.env.workspace = "c:/data/output.gdb"
fc = "c:/data/base.gdb/roads"
fields = ("ROAD_TYPE", "BUFFER_DISTANCE")
with arcpy.da.UpdateCursor(fc, fields) as cursor:
# Update the field used in Buffer so the distance is based on road
# type. Road type is either 1, 2, 3 or 4. Distance is in meters.
for row in cursor:
row[1] = row[0] * 100
cursor.updateRow(row)

7. arcpy.mapping: update/apply symbology
import arcpy
mxd = arcpy.mapping.MapDocument(r"C:ProjectProject.mxd")
df = arcpy.mapping.ListDataFrames(mxd, "Census")[0]
lyr = arcpy.mapping.ListLayers(mxd, "StatePopulation", df)[0]
lyrFile = arcpy.mapping.Layer(r"C:ProjectLYRsPopulation.lyr")
arcpy.mapping.UpdateLayer(df, lyr, lyrFile, True)
if lyr.symbologyType == "GRADUATED_COLORS":
lyr.symbology.valueField = "POP2000"
lyr.symbology.classBreakValues = [250000, 999999, 4999999, 9999999, 35000000]
lyr.symbology.classBreakLabels = ["250,000 to 999,999", "1,000,000 to 4,999,999",
"5,000,000 to 9,999,999",
"10,000,000 to 35,000,000"]
arcpy.mapping.ExportToPDF(mxd, r"C:ProjectOutputStatePopulation.pdf")
del mxd, lyrFile

8. Add-Ins

9. Python Toolboxes