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Intro to Python Welcome to the Wonderful world of GIS programing!

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Presentation on theme: "Intro to Python Welcome to the Wonderful world of GIS programing!"— Presentation transcript:

1 Intro to Python Welcome to the Wonderful world of GIS programing!

2 Topics A brief history of GIS programing What is Python? What is PythonWin? Basics of Python

3 Brief history of ESRI’s GIS software evolution Arc/Info Coverage 1980’s Software Data Format Year ArcView Shapefile 1990’s ArcGIS 8 & 9 Geodatabase 2000’s ArcGIS 10 Geodatabase 2010

4 Programming language SML was used for PC ArcInfo AML was used for Arc/INFO 7.x Avenue was used for ArcView 3.x Visual Basic for Application (VBA) is for ArcGIS 8 & 9 & packaged with it Python for ArcGIS10

5 What is Python? An object oriented scripting language Cross-platform: meaning portable & will run on Windows, Unix, and Linux Python is fully embraced by ESRI at ArcGIS 10 Comes bundled with ArcGIS Free

6 Programming Environments Python files are text files (.py extension) Python code can be written in Text Editor IDLE Python Win Python Window PythonWin is the preferred way!

7 PythonWin Interface 1.PyhonWin created specifically for windows with common tools & menus 2.Windows look and feel 3.3 windows: a. Application window b. Script window c. Interactive window

8 PythonWin: Script Window Script window is for writing, saving, & executing code Python scripts are saved extension. Ex: (

9 PythonWin: Interactive Window Interactive window is for testing code and report errors messages Also report the output of print statement

10 PythonWin: Application/main window Run ScriptCheck Script Script ran successfully

11 Basic Python syntax Comments Variables Strings Numbers

12 Comments Lines of code that serve as documentation: Non-executable Use a # or ## It’s a must for your lab Block of code can be commented -- Highlight the block of code in the script window -- Right click>Source Code>Comment out region Example: # Name: John Denver # Date: January 2012

13 Python Statements Lines of code that perform a task print- sends output to the interactive window import – import a module Example: print “Welcome to Python world” import math (import math module)

14 Variables Variables store values of different types first = ”Bob” last = “Brown” age = 30 height = 5.6 source = “C:/Exercises/Auburn.gdb” Variables are case sensitive Num = 500 & num = 5000 (2 variables) Variables are dynamically type -- do not have to declare the variable -- don’t have to assign a data type

15 Strings An ordered collection of characters Can be surrounded by double (“”) or single (‘’) quotes message = “Welcome to Python” input = “C:/GIS222/Auburn.gdb/roads”

16 Manipulating Strings Strings can be concatenated f1 = “C:/GIS222/Auburn/roads” f2 = “.shp” Data = f1 + f2 Result= “C:/GIS222/Auburn/roads.shp” Strings can be repeated s1 = “Ha!” s1*3 Result= “Ha!Ha!Ha!”

17 Common String Functions Upper, lower, capitalize,……….. f1 = “AUBURN.shp” f1.upper() Result: “AUBURN.SHP” There are many more; find them by typing object. f1.lower() Result: “auburn.shp” f1.capitalize() Result: “Auburn.shp f1.replace(“AUBURN”, “OWASCO”) Result: “OWASCO.shp”

18 Built-in Python Functions 2. round() returns a rounded number xCoord = 450,000.2345 round(xCoord) Result: 450,000 1. len() returns the length of a string or a list f1 = “AUBURN.shp” len(f1) Result: 10 3.str() converts an integer to a string zone = 18 strzone = str(zone) print “UTM Zone” + strzone

19 Other Functions to convert values 2. int() returns an integer value int(“10”) Result: 10 1. float() returns a floating point value float(“10.0”) Result: 10.0 3.str() converts an integer to a string str(18) Result: “18” print “UTM Zone” + str(18)

20 Getting user input 2. str = raw_input(“Enter your name: “) 1.num = input(“Enter you age: “) You can always check your input with print num Or print str

21 Python Tutorial Search: “What is Python” ArcGIS Resources Center:

22 Let’s try it!

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