1 of 57 GIS 4107 – Week 2. 2 of 57 Flow revisited Optimal balance between challenge and skill AnxietyArousalFlow WorryControl ApathyBoredomRelaxation.

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GIS 4107 – Week 2

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Flow revisited

Optimal balance between challenge and skill

Anxiety Arousal Flow

Worry Control

Apathy BoredomRelaxatio

n

Low High

High

Skill

Challenge

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Examples of Flow

Click on above image and wait for TED to load.Mouse over progress bar and then click on Compositionwhere she discusses the act of composition and flow.Then sit back and listen to the Improvisation segment.

Click on above image to go to this video.

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Talks on flow and creativity …

One of the best talks I have ever seen!

Relatively academic talk on the concept of flow and its relationshipto creativity and fulfillment.

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Flow

Csíkszentmihályi identifies the following as accompanying an experience of flow:

Clear goals (expectations and rules are discernible and goals are attainable and align appropriately with one's skill set and abilities). Concentrating and focusing, a high degree of concentration on a limited field of attention (a person engaged in the activity will have the opportunity to focus and to delve deeply into it). A loss of the feeling of self-consciousness, the merging of action and awareness. Distorted sense of time, one's subjective experience of time is altered. Direct and immediate feedback (successes and failures in the course of the activity are apparent, so that behavior can be adjusted as needed). Balance between ability level and challenge (the activity is neither too easy nor too difficult). A sense of personal control over the situation or activity. The activity is intrinsically rewarding, so there is an effortlessness of action. People become absorbed in their activity, and focus of awareness is narrowed down to the activity itself, action awareness merging

I highly recommend Csíkszentmihályi’s books “Creativity” & “Flow”

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Overview

Intro to …Computer hardware & softwareLow- and High-level languagesPython on Windows (install and use)Finding helpPython IDE’s (esp. PyScripter)

Intro to Python Programs & their partsExpressions, Operators, StatementsVariables (naming, assigning values, finding type)Core Python Types (esp. Numbers & Strings)Comments and line continuation

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Computer hardware

1. Input (keyboard, mouse, microphone, network, camera, etc.)

2. Output (screens, printers, network, etc)3. Primary Memory (RAM)

Fast read/write memoryStorage for OS, Applications, and dataData lost with power loss

4. Secondary Memory (Disks)Slow relative to primary memoryStorage for applications and data filesData persists with power loss

5. ALU (Arithmetic and Logic Unit)Perform calculations

6. CPU (Central Processing Unit)Manages operations between units

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Computer software

Everything that runs on a computer (even the boot sequence) is software written directly/indirectly by humans but computers do not understand human.System software

OS, System apps and services, etc

Application softwareWord processing, graphics, etc

Computers understand their own machine language; a system of instructions and data directly executed by a computer's central processing unit (CPU).

Computer program = Set of instructions a computer follows to perform a task = Software

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In computers: binary, everything, binary …

0’s and 1’s are the only thing acomputer can deal withHOWEVER, 0’s and 1’s can becombined into groups(e.g. 1 byte = 8 - 0’s & 1’s = 8 bits)Bytes and groups of bytes can be used to represent

Data Numbers, text, images, etc.

OperationsMath (+, -, *, /, etc), File I/O, CPU instructions, etc.Messages between devices (keyboard, mouse, web-cam, etc)

Decimal to binary conversion tool

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ASCII

ASCII - The American Standard Code for Information Interchange is a standard seven-bit code that was proposed by ANSI in 1963, and finalized in 1968.

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In 1968, ANSI did not think of this …

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Unicode

http://www.unicode.org/standard/WhatIsUnicode.html

http://www.unicode.org/Public/UNIDATA/UnicodeData.txt

Hex-to-decimal converter

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Pentium Instruction Set (x86 family)

From http://www.intel.com/design/pentium/manuals/24319101.pdf

Machine language is a bunch of 1’s and 0’s in specific patterns that a CPU understands.

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Low-level languages

Assembly is an example of a low-level language (close to machine language)

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High-level languages

High-level (English-like) computer programming languages can be used to create sophisticated computer applications and services.

NOTE: Not all high-level languages are converted to machine languageusing a compiler. Some use interpreters.

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Python (high-level lang) code and execution

Python.exe (and supporting files) handles interpretation of .py files or interactive commands into byte code (platform independent code) and statement-by-statement compilation in the Python Virtual Machine (runtime)

Python Interpreter

If not import’ed,bytecode is inmemory only

(i.e. no .pyc created)

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High-level Programming Languages

C-based• C (1972)• AWK (1977)• C++ (1983)• Perl (1987)• PHP (1995)• Java (1995)• JavaScript (1995)• C# (2000)• ASP.Net – C# (2002)

BASIC-based• Beginners All-purpose

Symbolic Instruction Code (BASIC) (mid-1960’s)

• Visual Basic 1 to 5 (1991 - 1998)

• Visual Basic 6 (VB6) (1998)

• Visual Basic for Applications (VBA) (1996 – 2007)

• VBScript (vbs) (1996)

• ActiveX Server Pages (ASP)

• VB.Net (2000)

• ASP.Net – VB (2002)

Non-C/BASIC-based languages includePython, Smalltalk, Eiffel, FORTRAN, COBOL, Pascal, etc.

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C vs VB vs Python

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Fundamental programming questions

How do you …Install/configure the development environment?Write code (syntax) and what are the code containers?Compile & run the code?Test and debug the code?Manage code (backups, versions, etc.)?Deploy application to users?

Where do you go for help?

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How do I install Python?

Usually installed with ArcGIS Python 2.4 with ArcGIS 9.2, 2.5 with 9.3, 2.6 with 10.0, 2.7 with 10.1

Download and run MSI from http://www.python.org

Python 2.x andPython 3.x are twodifferent developmentpaths of the languagee.g.

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Post-install configuration

Environment variablesMy Computer – Properties – Advanced tab – Environment variables (System variables panel)

PATH – need to add path to python.exe

PYTHONPATH – module search path (for imports) (optional)

PYTHONSTARTUP – path to interactive startup file (optional)

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How do I write and run Python code?

1. Interactively (if Python folder is in PATH)

2. Script from command-line

This works because .pyis associated with Python.exe

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How do I write and run Python code?

3. Script by double-clicking .py file in Explorer

The raw_input() function waits for input from keyboard

(e.g. pressing enter)

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How do I write and run Python code?

• Run script using IDE buttons or keyboard shortcuts• Interactively in Python Interpreter window

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.py files and Python.exe

How does computer know .py files should be run using Python.exe?

In Explorer, Tools menu > Folder options > File types tab

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Where do I go to learn more?

Python mother shiphttp://www.python.org

Any book by Mark Lutz (e.g. Learning Python, 3rd ed)

Google with “python” and some other keyword

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Docs, help() and dir()

Docs: • http://www.python.org/doc • ActivePython27.chm

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Integrated Development Environment – IDE

IDLE is a Python IDE that comes bundled with the Python installation (cross-platform)

PythonWin (part of ActivePython) is a Windows-only IDE

From http://www.activestate.com

PyScripter is the Python IDE we will use in this course

From http://code.google.com/p/pyscripter/ Source code available using Subversion client from http://pyscripter.googlecode.com/svn/trunk/

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IDLE

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PythonWin

Shortcuts:Alt + I = word completion (intellisense)Ctrl + A = select all text in windowCtrl + A then Delete = clear windowCtrl + Up arrow = previous commandCtrl + Down arrow = next command

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PyScripter

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Installing PyScripter from EXE

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Overview

Intro to …Computer hardware & softwareLow- and High-level languagesPython on Windows (install and use)Finding helpPython IDE’s (esp. PyScripter)

Intro to Python Programs & their partsExpressions, Operators, StatementsVariables (naming, assigning values, finding type)Core Python Types (esp. Numbers & Strings)Comments and line continuation

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Python Programs & their parts …

Python programs are usually composed of Modules (.py files)Modules are composed of statementsStatements contain one or more expressionsExpressions create and process objects

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Expressions and statements

Expressions are valid combination of one or more …

Variable names – e.g. recordCount, x, fileName, etc.

Python keywords – e.g. print, input, raw_input, exit, etc.

Operators - e.g. +, -, *, /, etc. Operands to the left and right

Literals - e.g. 2, “Spam”, etc.

Delimiters - e.g. (" , . : ')

Expressions can beArithmetic (output is a number)

Boolean (output is True or false)

A function call

etc.

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Language Keywords

All programming languages have keywords that are “reserved” (can’t be used for other purposes) and are the for all coding

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Expression List and Statements

An expression on one line is a statement

More than one expression separated by commas is an expression list

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Variable = Name associated with a value/object

Objects are created and names are associated with them. In this example, the 1 has two names associated with it.

Names are case sensitive

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Rules for variable naming

Variable name syntax:_ or letter + any number of letters, digits, or _i.e. cannot begin with a number

Use names that describe the data they are associated with

e.g. “recordCount” is better than “n”

Use lowercase letter for first character, upper case letter for other words in name. This is called Camel Case.

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Variables and assignments

Assignments create variables that are associated with values/objects

The following statement creates an integer in memory and associates it with the name x x = 1

Variables are created when they are first assigned

Variable names are not declared like C# with type int x;

Variables must be assigned before they are used

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PEMDAS / BEMDAS

Operator precidenceParentheses/BracketsExponentiation Muliplication – DivisionAddition - Subtraction

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dir() and del

The dir() function will display a list of all currently accessible modules and variables

The del command will delete the named variables

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Determine an variables type with type()

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Core object types

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Core object types: Numbers

A category of similar object typesIntegers (1234)Long integers (unlimited size!)Floating point (123.4)Octal (0177) & Hex (0XFF)Complex (3.0+4j)

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Numbers: Standard operations

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Numbers: Up conversion

Python converts operands up to type of most complicated operand before performing math on same-type operandsWith float data types, the least significant bits can cause small “errors”

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Numbers: Getting remainder of division

Finding whether or not a number is a factor of another numberUseful for finding whether or not a number is even(e.g. 4 % 2 = 0, 3 % 2 = 1)Use the modulo operator (%)

641

-42

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Core object types: Strings

Strings=ordered collections (sequence) of charactersCan be enclosed by single or double quotes

len() built-in for getting length of strings

Many built-in string methods …

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Escape sequences and raw

Backslash with one or more characters to support special byte codings

\n = newline\t = horizontal tab\\ = backslash\xhh = hex (e.g. \xFF = 255)

r = raw = …

Extended ascii table …

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Multiline block strings """ …. """

Triple double- or single-quotes multiline stringsThe \n is inserted automatically

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Concatenation, repetition, “in”

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Dynamic typing and operator polymorphism

Expressions determine the initial type of object and this can be changed dynamically (dynamically typed)Objects support calls to methods supported by that objectOperators (e.g. +, *) are polymorphic

i.e. Behaviour depends on object types on either side

Note: In interactive mode, statement output is echoed to the screen. In file mode (run from Command tool or in IDE), statement output is not displayed without print.

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Built-in operators and functions

Expression operators: +, -, *, /, **, >>, etc.Built-in functions: str(), abs(), etc.Type conversions: int(), float(), long(), str(), etc.Utility modules: math, random, NumPy, etc.Logical operators: ==, !=, <, <=, or, and, not, etc.

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Line continuation

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Comments

“The best kind of comments are the ones you don't need. Allow me to clarify that point. You should first strive to make your code as simple as possible to understand without relying on comments as a crutch. Only at the point where the code cannot be made easier to understand

should you begin to add comments.” From http://www.codinghorror.com/blog/archives/000749.html

Use # for single line or """ """ for multi-line comments.

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We’re done