The Arc Macro Language

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Lecture 7

• The Arc Macro Language

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This Lecture

• What is AML?
• Command line ArcGIS.
• Some basic concepts.
• Using variables and functions.
• Controlling program flow.
• Graphical User Interfaces (GUIs)

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Textbook

• ESRIs ARC Macro Language Developing ARC/INFO
  Menus and Macros with AML Self-study Workbook
  Version 7.1.1 for UNIX and Windows NT

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What is AML?

• A simple programming language in a text file.
• Interpreted not compiled.
• Runs in the order that commands, directives, etc.
  appear in the program.
• A way to automate tedious tasks in ArcGIS.
• A way to write (old skool) interfaces.
• Allows you to write programs that
• manipulate ArcGIS objects such as Coverages and
  INFO files
• customise ArcGIS applications
• increase productivity.

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Example Tasks

• Running batch jobs.
• Automating frequently performed tasks.
• Combining two or more existing commands to create
  a new one.
• Creating menu driven interfaces.
• Integrating spatial models with ArcGIS.
• Standardising procedures for other people.

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A Simple Example

• / program.aml
• type Creating coverage topology
• build buildings poly
• clean buildings
• type Hello World!
• return
• Arc run program.aml
• At its most basic an AML program is just a list
  of ArcGIS commands. You can usually guess the Arc
  command from the ArcDesktop tools name.
• With some ArcDesktop tools theres a Save to AML
  button. This gives an AML file you can edit or
  copy from.

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Parts of AML

• Arc Commands
• build, clean, etc.
• Variables - delimited by
• i, cover
• Functions - delimited by
• exists cover -point
• Directives - preceded by
• return, type, if, goto, etc.
• Comments - preceded by /
• / I heart ArcGIS (as in stab in the).

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Syntax

• AML isnt case sensitive.
• But remember, some parts of ArcGIS are, so if you
  are using AML to pass it commands, the commands
  need to be the right case.
• Some directives have abbreviations.
• setvar cover landuse
• sv cover landuse
• s cover landuse

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Basic Layout

• / bldcln.aml
• echo on
• build roads line
• clean roads
• roads_c line
• build stations point
• build urban poly
• clean urban
• return
• Arc run bldcln.aml
• return ends the program and returns to the
  command line.
• echo on will write the commands on the screen
  as they are done. echo off will stop this.
• continues commands onto the next line. The
  bold lines above are all one command.

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Variables

• Like a name you can attach to a value or set of
  text.
• Variables are set using setvar directive.
• sv cover landuse
• sv cover landuse
• sv cover landuse
• Variables store 4 data types.
• Character string, e.g. buildings
• Integer number, e.g. 23
• Real number, e.g. 4.242
• Boolean value, can be .TRUE. or .FALSE.
• listvar (lv or l) displays list of currently
  assigned variables.

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Using Variables

• When using Variables theyre delimited by
  except when being assigned.
• sv cover landuse
• build cover poly
• Variables can be used together.
• sv cover landuse
• sv infotab pat
• sv item landuse_type
• dropitem cover.infotab cover.infotab
  item
• Which is the same as...
• dropitem landuse.pat landuse.pat landuse_type

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Local vs. Global Variables

• So far weve looked at Local Variables that work
  in a single AML script.
• However, you can define Global Variables that
  work throughout an Arc session.
• Global Variable names begin with a
  fullstop/period (.)
• sv .cover landuse
• build .cover poly
• listlocal and listglobal directives do just
  what they say.

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Reserved Variables

• These contain information held internally by the
  system including information about
• data (DSC)
• the graphical cursor/pointer (PNT)
• the status of AML programs (AML)
• DSCFUZZY fuzzy tolerance.
• PNTX x co-ordinate selected.
• AMLFILE the current file being run.
• Dont assign these yourself.
• See ArcDocs gt Customizing ArcInfo gt AML gt Using
  Variables gt Reserved Variables

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Using Reserved Variables DESCRIBE

• The describe function takes in a Coverage and
  sets up various reserve variables containing data
  on the Extent, number of Tics etc.
• See ArcDocs gt Command References gt AML gt
  Describe.
• describe newBuildings
• sv numpoly DSCPOLYGONS
• type numpoly

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Command Line Arguments

• So far weve looked at running AMLs with no
  arguments
• run plot
• You can pass arguments to an AML when you run
  them, for example
• run plot roads blue
• Use the args directive to get the values. Should
  be first directive except for echo.
• args ltvariable...variablegtrest
• For example
• args cover colourrest
• rest sticks any remaining text in the last
  Variable. ie for this example colour.

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Using Command Line Arguments

• Example
• Arc run plot roads blue
• args cover colourrest
• arcedit
• mapextent cover
• edit cover
• de arc node
• nodecolor node colour
• draw
• return

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Functions

• Functions perform the following operations
• prompting for user input
• calculating mathematical values
• modifying extracting values from character
  strings
• reporting current conditions
• reading and writing files.
• Functions and their options are enclosed by
  square brackets .
• s covername getcover
• Write your own functions write AMLs taking in
  arguments and use run / amlpath to call them in
  other AMLs.

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Directives Controlling Program Flow

• We can put in decision making (branching) and
  repetition (looping) in AML.
• Can branch on the basis of user inputs or
  calculations if something do something,
  otherwise do something else.
• Can repeat to do multiple calculations given a
  list, run through each item and do something to
  them.

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Branching with If

• If the expression equals .TRUE. then the actions
  1 are done, otherwise the actions 2 are done. The
  rest of code is done whatever.
• You dont need to have the else section.
• Also if you just have one action, you dont need
  the do and end.
• if ltexpressiongt
• then ltactionsgt
• ltrest of codegt

if ltexpressiongt then do ltactions 1gt
end else do ltactions 2gt end /
Rest of code
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Expressions

• if username bob then
• type hello bobster
• else type do I know you?
• The expression username bob equates to either
  .TRUE. or .FALSE. These are known as Logical
  Expressions.
• Examples of logical expressions
• 3 6 10 equates to .False.
• 3 6 9 equates to .True.
• date -dow Sunday equates to .False.
• AML makes the comparison using Relational
  Operators like or lt, lt, gt, gt, ltgt.

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Looping

• Iterative steps can be performed in AML using an
  do end loop
• The do loop structure
• do ltloop control clausegt
• ltaction 1, 2...ngt
• end
• There are four types of do end loop
• Counted, List, While, Until.

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Counted Loops

• Used when the number of iterations is known
• do i ltstartgt to ltstopgt by ltincrementgt
• ltaction 1,2,...ngt
• end
• i ltloop control variablegt

do burgers 1 to 3 by 1 type Eaten
burgers end type Elvis ate burgers
burgers return
Eaten 1 Eaten 2 Eaten 3 Elvis ate 3 burgers
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Listed Loops

• Performs a set of identical actions on a list of
  elements (e.g. coverages)
• do i list ltlist of elementsgt
• ltaction 1gt
• ltaction 2gt
• ltaction ngt
• end
• i ltloop control variablegt

• do food list burger squirrel coke
• type food
• end

burger squirrel coke
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While and Until Loops

• Used when the number of iterations is not known,
  but while or until a specified condition is met
• do while ltlogical expressiongt
• ltaction 1,2,...ngt
• end
• do until ltlogical expressiongt
• ltaction 1,2,...ngt
• end

do until query 'Do you feel sick yet?'
type Another burger, thankyverymuch. end
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Debugging

• Debugging programs - finding and fixing errors.
• Three useful commands.
• echo on writes all commands and outputs to
  the screen.
• test on puts Arc in AML test mode actions
  arent done, but the syntax and possibility of
  running are checked.
• messages on sets Arc so it gives messages
  about what its doing (usually this is set as the
  default).
• test on
• sv cover landuse
• build cover poly
• return
• Arc also has Error Handling, which lets you
  determine where errors come from and deal with
  them. See Error handling in AML in the ArcDocs.

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Menus Building a GUI

• A menu is a graphical list of options from which
  the user can select a choice.
• AML includes easy-to-use tools for creating
  menus.
• Menus can be used for
• creating GUIs for inexperienced users
• eliminating errors by showing only valid options
• customising user interfaces
• creating highly visual demonstrations
• reducing the amount of typing.
• See, for example, ArcTools.

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Menus from AML Scripts

• AML Functions beginning with get... create
  menus for you.

Function Menu choices offered
getchoice user defined choices
getcover coverage names
getfile directory or file names
getgrid grid names
getitem item names in INFO file
getsymbol symbols of specified type
gettin tin names
getunique unique item values in INFO
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Examples

• getcover

sv cov getcover
sv cov getcover -POLYGON 'Choose a
Coverage'
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Separate Menus

• get functions are OK but you cant easily
  control
• where they decide to appear on the screen
• what they look like
• what they do.
• Menu files are
• ASCII files
• named with .menu extension
• run with menu directive.
• Must set display environment with terminal to
  let AML know the device type before use (also
  true for get). E.g. terminal 9999

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Menu Types

• 8 supported types
• 1 pulldown
• 2 sidebar
• 3 matrix
• 4 key
• 5 tablet
• 6 digitiser
• 7 form
• 8 enhanced pulldown

• Youre most likely to use
• pulldown
• sidebar
• form
• enhanced pulldown.

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Enhanced Menu
Makes Landuse Use Alt-L to use

• 8 A sample enhanced pulldown menu
• BEGIN_MENU
• BEGIN_BLOCK "Landuse"
• MENUITEM "Draw" POLYGONSHADES LANDUSE
  LU-CODE LAND.LUT
• SEPARATOR
• MENUITEM "List" LIST LAND POLY
• END_BLOCK
• BEGIN_BLOCK "Sewers"
• MENUITEM "Draw" ARCLINES SEWERS SYMBOL
• MENUITEM "List" LIST SEWERS ARC
• END_BLOCK
• BEGIN_BLOCK "Option"
• MENUITEM "Clear" CLEAR
• MENUITEM "Quit" RETURN
• END_BLOCK
• END_MENU

Separator
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MenuEdit

• Started by typing menuedit.
• Automatically generates your menus and allows you
  to save them to a .menu file.

This allows you to make submenus with Pull
Right. The test facility brings up a test
version.
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Forms

• A powerful menu extension allowing dynamic GUIs.
• Windows based editor (type formedit) allows you
  to add
• Command Buttons
• Check boxes(multiple section)
• Radio buttons (one selection from group)
• Slider bars (scrollbars)
• Text boxes
• Lists.
• Add items by clicking on the icons then in the
  Form.

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Form Elements

• Three kinds
• text control for displaying descriptive text or
  labels
• display control for displaying the contents of
  a variable to the user
• input controls allows user to enter in text or
  values.
• All set up with Right click gt Properties.

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Text Control

• Used as a piece of descriptive text or in front
  of an input control.
• Cannot resize but it will adjust to fit the size
  of the string you type in.

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Display Control

• Used for holding dynamic text, i.e. things that
  can change during the course of the program.
• For example, you might want to process Coverages
  and then add their names to a display when
  finished.
• You can resize this control.

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Input Control

• Returns you a variable and value (can be global),
  or starts an action.
• Some give you the option of setting up error
  messages (On Error tab).

For keyboard navigation (usually the SHIFT key)
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Customizing ArcTools

• You can add Menus and AML to ArcTools in
  ArcWorkstation and ArcToolbox.
• These are just AML/Menu files in particular
  directories written in a particular format.
• You can find more details of adding them to
  ArcTools in the ArcDocs under Customising
  ARC/INFO gt Programming ArcTools.

• Note ArcGIS8.x You cant add full AML to
  ArcToolbox, however, you can run AML from it
  provided
• It only uses Arc and Info commands (i.e. no
  ArcEdit).
• It doesnt use Menus.

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Further info

• The ArcDocs arent terribly helpful on Forms,but
  theres stuff on Menus and AML in Customizing
  ARC/INFO.

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Next Lecture

• VBA