Python gis
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This document introduces Python scripting in ArcGIS and provides resources for learning Python. It discusses when scripting is needed in GIS workflows and provides an example Python script to add watermarks to photos. It also summarizes key benefits of Python like high productivity, portability and large standard and third party libraries. Advanced topics covered include accessing geoprocessing tools and mapping functionality from Python scripts. Links are provided to online courses and tutorials for learning Python programming.
![An ugly case in point
#Python Script for putting watermark annotationon image
#John Zhou MWH Global 12/19/2006
#Fragile,not for other use
#need Python and PIL Installed
import win32com.client
import fnmatch
import string
import os
import Image,ImageDraw,ImageFont,sys
engine = win32com.client.Dispatch("DAO.DBEngine.36")
strPath="E:PWP_WaterMark"
#Determinethe path to your databaseand use the following
syntax:
#makesure the database name
db =
engine.OpenDatabase(strPath+"ConsolidatedGPS_18Dec2006.m
db")
totalNum=0
ferr=open("c:err.txt","w")
fsuccess=open("c:success.txt","w")
for fileNamein os.listdir( strPath+"FieldPhotos"):
if fnmatch.fnmatch( fileName, '*.jpg' ) :
path, name = os.path.split (fileName)
queryString="selectPoleFacilityID, Address,PhotoLocation from
Pole where PhotoLocation like '*" +name+"*'"
# print queryString
x=1
rs = db.OpenRecordset( queryString)
Anno=""
while not rs.EOF and x<2:
Anno= rs.Fields("PoleFacilityID").Value+"|"+rs.Fields("Address").Value+
"|"+name
rs.MoveNext
x=x+1
strFileName= strPath+"FieldPhotos"+fileName.upper()
totalNum=totalNum+1
if (len(Anno)>0):
fsuccess.write(strFileName+"n")
else:
ferr.write(strFileName+"n")
# print strFileName
im1=Image.open(strFileName)
im2=Image.new(im1.mode,im1.size)
font = ImageFont.truetype("arial.ttf",16)
textsize=font.getsize(Anno)
for mySize in range(18,100,2):
if textsize[0]>=im1.size[0]-im1.size[0]*0.2:
break
font = ImageFont.truetype("arial.ttf",mySize)
textsize=font.getsize(Anno)
draw2=ImageDraw.Draw(im2)
draw2.rectangle([0,im2.size[1],im2.size[0],im2.size[1]-
textsize[1]],fill=128)
im3=Image.blend(im1,im2,0.2)
draw3=ImageDraw.Draw(im3)
draw3.text(((im3.size[0]-textsize[0])/2,im3.size[1]-textsize[1]), Anno,
font=font)
im3.save(strFileName,"JPEG")
print totalNum
ferr.close()
fsuccess.close()](https://image.slidesharecdn.com/python-gis-150728172100-lva1-app6892/85/Python-gis-4-320.jpg)
Python gis
- 2. What do we usually do with GIS
- 3. When do we need scripting
- 4. An ugly case in point #Python Script for putting watermark annotationon image #John Zhou MWH Global 12/19/2006 #Fragile,not for other use #need Python and PIL Installed import win32com.client import fnmatch import string import os import Image,ImageDraw,ImageFont,sys engine = win32com.client.Dispatch("DAO.DBEngine.36") strPath="E:PWP_WaterMark" #Determinethe path to your databaseand use the following syntax: #makesure the database name db = engine.OpenDatabase(strPath+"ConsolidatedGPS_18Dec2006.m db") totalNum=0 ferr=open("c:err.txt","w") fsuccess=open("c:success.txt","w") for fileNamein os.listdir( strPath+"FieldPhotos"): if fnmatch.fnmatch( fileName, '*.jpg' ) : path, name = os.path.split (fileName) queryString="selectPoleFacilityID, Address,PhotoLocation from Pole where PhotoLocation like '*" +name+"*'" # print queryString x=1 rs = db.OpenRecordset( queryString) Anno="" while not rs.EOF and x<2: Anno= rs.Fields("PoleFacilityID").Value+"|"+rs.Fields("Address").Value+ "|"+name rs.MoveNext x=x+1 strFileName= strPath+"FieldPhotos"+fileName.upper() totalNum=totalNum+1 if (len(Anno)>0): fsuccess.write(strFileName+"n") else: ferr.write(strFileName+"n") # print strFileName im1=Image.open(strFileName) im2=Image.new(im1.mode,im1.size) font = ImageFont.truetype("arial.ttf",16) textsize=font.getsize(Anno) for mySize in range(18,100,2): if textsize[0]>=im1.size[0]-im1.size[0]*0.2: break font = ImageFont.truetype("arial.ttf",mySize) textsize=font.getsize(Anno) draw2=ImageDraw.Draw(im2) draw2.rectangle([0,im2.size[1],im2.size[0],im2.size[1]- textsize[1]],fill=128) im3=Image.blend(im1,im2,0.2) draw3=ImageDraw.Draw(im3) draw3.text(((im3.size[0]-textsize[0])/2,im3.size[1]-textsize[1]), Anno, font=font) im3.save(strFileName,"JPEG") print totalNum ferr.close() fsuccess.close()
- 5. What about Model Builder Model Builder is a great way to lay out a geoprocessing workflow, but some functionality is just not available Models can be exported to scripts Exported scripts can be modified to support more complex logic and looping Good way to learn tool usage and python syntax
- 6. Why Python Python is an open-source object-oriented programming language that offers two to ten fold programmer productivity increases over languages like C, C++, Java, C#,Visual Basic (VB), and Perl. excellent for beginners, yet superb for experts highly scalable, suitable for large projects as well as small ones portable, cross-platform powerful standard libs wealth of 3rd party packages/modules (numPy, SciPy)
- 7. # Create Geoprocessing object import arcgisscripting gp = arcgisscripting.create(9.3) # Set the workspace gp.workspace = "c:/st_Johns/GISData.gdb“ # use Geoprocessing tool gp.intersect("roads;urban_area", "urban_roads", 5, "join") # run a tool gp.Buffer("c:/ws/roads.shp", "c:/outws/roads10.shp", 10) # Print the tools messages to screen print gp.GetMessages() #0-informative, 1-warning, 2-error, blank-all messages # Get a list of all polygon feature # classes in the workspace fcList = gp.ListFeatureClasses("*", "polygon") # Print the list of feature classes one at a time for fc in fcList: print fc Infeatures = gp.GetParameterAsText(0) Outfeatures = gp.GetParameterAsText(1) Access to all toolbox tools Details: http://webhelp.esri.com/arcgisdesktop/9.3/body.cfm?tocVisable=1&ID=920&TopicName=Running%20a%20tool# Anatomy of ArcGIS Python
- 9. http://webhelp.esri.com/arcgisdesktop/9.3/pdf/Geoprocessor_93.pdf Programming Model
- 10. Advanced Topic - ArcPy Mapping (10) http://resources.arcgis.com/gallery/file/geoprocessing/details?entryID=A910AB18-1422-2418-3418-3885D388EF60(arcpy.mapping sample script tools) http://blogs.esri.com/dev/blogs/arcgisdesktop/archive/2010/12/14/combining-data-driven-pages-with-python-and-arcpy.mapping.aspx (Combining Data Driven Pages with Python acrpy.mapping)
- 11. For those committed http://code.google.com/edu/languages/google-python- class/introduction.html (PyQuick class by Google) http://training.esri.com/acb2000/showdetl.cfm?DID=6&Pro duct_ID=971 (Using Python in ArcGIS Desktop 10, web course) http://proceedings.esri.com/library/userconf/devsummit10/ tech/presumm_04.html (Getting Started with Python in ArcGIS) http://docs.python.org/tutorial/introduction.html (Python Tutorial) Books Learning Python by Mark Lutz Core Python by Wesley J. Chun Dive Into Python by Mark Pilgrim