What is AML?

• What is a program?

• What is AML?

• An AML can:– Automate frequently performed actions– Provide a quick and consistent way to set

environments– Decide what to do– Do things over and over

• An AML can: (.cont)– Interact with users using text or menus– Run other AMLs and programs

• Running an AML• Useful tips - &echo and &pause• Watch files

– Recording your session with a watch file– Converting a watch file to an AML

What is a program?

Begin

End

Set mapextent

Shade polygons

Draw legend

A series of instructions

Advantages of programming

• Reduces typing errors

• Maintains consistency

• Documents your work

• Automates repetitive tasks

• Offers new users a way to be more productive

AML programs can branch

AML programs can respond with an appropriate action by branching

Begin

End

Set mapextent

Shade polygons

Draw legend

End

Build TopologyAnd

Shade polygonsYes NoDoes the

coveragehave polygon

topology?

AML programs can loop

An AML program can repeat procedures

Begin

Draw coverage

End

Do you want to draw a coverage?

No

Yes

Do you want to draw

another coverage?

NoYes

AML programs can communicate with users

By selectingfrom menusBy typing

from a keyboard

Picture a keyboard

AML programs can communicate with other programs

AML programs can run other programs (modules)

Begin

Get a coverage

End

Check topology

Draw coverage

Menu to get a coverage

Program to check topology

Program to draw a coverage

AML programs should be clear and reliable

• Document AML programs

• Test AML programs

• Handle errors gracefully

Designing an application

• Determine functionally– User needs assessment

• System design strategies– Data flow diagram

Flow charts•Map out the logic of a program•Use different symbols for different actions

Beginor end

Get a coverage

Menu to get a coverageDecision

Flow

Action

Separate module

Pseudocode•Represents the flowchart in a common language•No code words should be used in the pseudocode

Sample pseudocode:

Get a coverage name from the user

If the coverage has both polygon and line topology then Allow the user to choose either polygon or line topology

If the coverage has only line topology then Allow the user to choose only line topology

If the coverage has only point topology then Allow the user to choose only point topology

Establish where on the screen the coverage will be displayedDisplay the coverage on the screen

The Header

Name

Purpose

Arguments

Global VariablesLocal Variables

CoveragesDetailed Remarks

Other Amls, Menus

History

Major components of AML

• Directives are AML “commands”– Begin with an &

• Variables store a value– Surrounded by % %

• Functions return a value– Surrounded by [ ]

AML directives

• The first character is always an ampersand (&)– Example: &watch, &run, &popup

• AML directives work anywhere– (e.g., ARC, ARCPLOT, ARCEDIT)

• ARC: &run test.aml• Arcplot: &popup test.aml• Arcedit: &watch edit.wat

DirectivesThis directive: …tells AML to:

&TERMINAL Sets the terminal type

&ECHO Display lines of program asthey are executed

&PAUSE Wait for the user to hit thereturn key

&WATCH Captures the session in awatch file

&SHOW List the current value of anAML program or menu

&TYPE Print a message at theterminal

Variables: %cov%

• Store a value

• Set variables with the &setvar directive

– Arc: &setvar cover = soil

• Use percent signs (%) to evaluate a variable– Arc: DESCRIBE %cover%

– is the same as:

– Arc: DESCRIBE soil

• Variable names are not case sensitive– Arc: DESCRIBE %cover%

– is the same as:

– Arc: DESCRIBE %COVER%

Local, global, and program variables

• Local variables– No dot (.) at beginning of name– Only available to the current AML program

• Global variables– Starts with a dot (.)– Available to all AML programs

• Program variables– Start with a colon (:)– Available to all AML programs

• Examples:• :PROGRAM is automatically set• to the current program

&s cov = streetARCS %cov%&return

Draw.aml

&s .cov = street&r resetARCS %.cov%&return

Redraw.aml

Arc: &lpprogram: :PROGRAM ARC

Functions •Returns values•Enclosed within square brackets [ ]

This function: …tells the AML processor to and returns:[GETCOVER] Displays a menu of coverages /tom/street

[RESPONSE] Ask the user to type some text Enter text

AML Example: buildpoly.aml BUILD [response ‘Enter the coverage to build’] poly

End part 1

How to ask a question of a user with function statements

[RESPONSE]•Prompts the user to enter a response (accepts any text)•Text that the user types becomes the return value of the function

•Arc: &s answer = [RESPONSE ‘Type ARC or POLY’]•Type: ARC or POLY: POINT•Arc: &type The user typed %answer%•The user typed POINT

[QUERY]•Accepts only a yes or no answer from the user•Returned value is .TRUE or .FALSE.

•Arc: &s continue = [QUERY ‘Do you want to kill the coverage’ .FALSE.]•Do you want to kill the coverage? YES•Arc: &type %continue%• .TRUE

Branching

• Obtaining information about a coverage

• &IF statements - &IF &THEN

• Logical expressions

• Indention

Getting information about a coverage

• ARC command: DESCRIBE <geo_dataset>– Displays <geo_dataset> characteristics on the screen

– Sets AML reserved variables for the <geo_dataset>

• AML directive: &DESCRIBE <geo_dataset>

– Only sets the AML reserved variables for the <geo_dataset>

– Can be executed from any Arc/Info environment

– Coverage examples:• THIS VARIABLE CONTAINS THIS VALUE• DSC$ARCS Number of arcs• DSC$POINTS Number of points• DSC$POLYGONS Number of polygons• DSC$TOPOLOGY .TRUE. If polygon topology is present

.FALSE. If not• DSC$QEDIT .TRUE. If coverage has been edited .FALSE.

If not

Handouts p4-5

Blocks of statements

• &DO &END– Every &DO must have an &END– Groups related code into a single block– Can be substituted for the single statement

of &IF &THEN– Example:

&IF [NULL %cov%] &then &do &sv cov = [GETCOV] &type Cover is %cov% &endARCS %cov%

A block

Decision making example

Describe the coverage

End

Draw them red

Yes

No

Does the coverage have

arcs?

&describe %cov%

&if %des$arcs% > 0 &then &do LINECOLOR RED ARCS %cov% &end&END

&ELSE

Describe the coverage

Draw them redYes

No

Does the coverage

have arcs?

Error message

&describe %cov%

&if %dsc$arcs% > 0 &then &do LINECOLOR RED ARCS %cov% &end

&else &do &type ERROR - NO ARCS &end

&ELSE &IF

Describe the coverage

Draw them redYes

No

ARCS > 0?

Draw points green

&describe %cov%

&if %dsc$arcs% > 0 &then &do LINECOLOR RED ARCS %cov% &end&else &do &type ERROR - NO ARCS &end&else &if %dsc$points > 0 &then &do MARKERCOLOR GREEN POINTS %COV% &end&else &do &type ERROR - NO POINTS &end&END

Points > 0?Yes

Error messageNo

Error message

Looping

• Nesting loops• Making a decision at the beginning of a loop• Making a decision at the end of a loop

• &do &to &by• &do &list• &do &repeat• &do &until• &do &while

Controlling the number of loopsFour basic ways

•Count up to a set number &do&to&by

•Loop once for each element in list &do &list

•Make a logical decision at the• beginning of the loop &do &while

•Make a logical decision at the• end of the loop &do &until

Counting &do loops

• AML coding Results • &do i - 1 &to 5 I = 1• &type i = %i% I = 2• &end I = 3• I = 4• I = 5

• The default auto increment is one

Nesting &do loopAML coding

&do outside = 1 &to 3 &do inside = 100 &to 400 &by 100 &type outside = %outside% inside = %inside% &end /* inside do loop&end /* outside do loop Results:

outside = 1 inside = 100outside = 1 inside = 200outside = 1 inside = 300outside = 1 inside = 400outside = 2 inside = 100outside = 2 inside = 200outside = 2 inside = 300outside = 2 inside = 400outside = 3 inside = 100outside = 3 inside = 200outside = 3 inside = 300outside = 3 inside = 400

Making a decision at the beginning of a loop

Use &DO &UNTIL

&s color = 1 &do &until not [QUERY ‘DRAW ANOTHER COVERAGE’] LINECOLOR %color% ARCS [GETCOVER] &s color = %color% + 1 &end /* DO

Will always execute at least once The first coverage is drawn before the user sees the question asking to draw another coverage

The loop terminates when the condition is .TRUE.

Write an AML program that accepts user input:

Use your text editor to write a simple startup AML program (Start.aml)

1) Have your AML program get a coverage and copy it to a new coverage as the coverage name version 2.

2) Have the AML program open ArcPlot and select an arc coverage, and draw the coverage to the screen in red.

3) Add to your AML the ability to select a coverage and decide if it has arcs and draw it in red, or if no arcs display an

error message

4) Add to your AML the ability to keep asking to draw more coverages.

Do

the

se o

ne at a

time

Ma

ke sure each

on

e w

orks

befo

re yo

u go to

the

ne

xt one

!

Changing formats on an image

Begin

Get an image

Decision

Ask for name of a grid

Convert to a grid Convert an image

Kill the grid

end

&do &while [Query 'Do you want to convert an~ image:' .false] &s image = [getimage # -tiff 'Select an image to convert:'] &s grid = [response 'Enter the grid name']

IMAGEGRID %image% %grid% GRIDIMAGE %grid% GRAY %grid% TIFF KILL %grid% ALL

&type 'You just created an image named' %grid%'.tif'&end

Yes

No

End