SPSS Usersguide12 Syntax

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Chapt12Working withCommand Syntax

SPSS provides a powerful command language that allows you to save and automate

many common tasks. It also provides some functionality not found in the menus

and dialog boxes.

Most commands are accessible from the menus and dialog boxes. However, som

commands and options are available only by using the command language. Thecommand language also allows you to save your jobs in a syntax file so that you ca

repeat your analysis at a later date or run it in an automated job with the Production

Facility.

A syntax file is simply a text file that contains commands. While it is possible to

open a syntax window and type in commands, it is often easier if you let the softwa

help you build your syntax file using one of the following methods:

Pasting command syntax from dialog boxes

Copying syntax from the output log

Copying syntax from the journal file

In the online Help for a given procedure, click the command syntax link in the

Related Topics list to access the syntax diagram for the relevant command. For

complete documentation of the command language, refer to the SPSS Command

Syntax Reference.

Complete command syntax documentation is automatically installed when you

install SPSS. To access the syntax documentation:

E From the menus choose:

Help

Command Syntax Reference

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Chapter 12

Syntax Rules

Keep in mind the following simple rules when editing and writing command syntax:

Each command must begin on a new line and end with a period (.).

Most subcommands are separated by slashes (/). The slash before the first

subcommand on a command is usually optional.

Variable names must be spelled out fully.

Text included within apostrophes or quotation marks must be contained on a

single line.

Each line of command syntax cannot exceed 80 characters.

A period (.) must be used to indicate decimals, regardless of your Windows

regional settings.

Variable names ending in a period can cause errors in commands created by

the dialog boxes. You cannot create such variable names in the dialog boxes,

and you should generally avoid them.

Command syntax is case insensitive, and three- or four-letter abbreviations can be

used for many command specifications. You can use as many lines as you want to

specify a single command. You can add space or break lines at almost any point

where a single blank is allowed, such as around slashes, parentheses, arithmetic

operators, or between variable names. For example,

FREQUENCIES

VARIABLES=JOBCAT GENDER

/PERCENTILES=25 50 75

/BARCHART.

and

freq var=jobcat gender /percent=25 50 75 /bar.

are both acceptable alternatives that generate the same results.


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Working with Command Syn

INCLUDE Files

For command files run via the INCLUDE command, the syntax rules are slightly

different:

Each command must begin in the first column of a new line.

Continuation lines must be indented at least one space.

The period at the end of the command is optional.

Unless you have existing command files that already use the INCLUDE command,

you should probably use the INSERT command instead since it can accommodate

command files that conform to either set of rules. If you generate command syntax

by pasting dialog box choices into a syntax window, the format of the commands is

suitable for any mode of operation. See the Command Syntax Reference (available PDF format from the Help menu) for more information.

Pasting Syntax from Dialog Boxes

The easiest way to build a command syntax file is to make selections in dialog box

and paste the syntax for the selections into a syntax window. By pasting the syntax

each step of a lengthy analysis, you can build a job file that allows you to repeat the

analysis at a later date or run an automated job with the Production Facility.

In the syntax window, you can run the pasted syntax, edit it, and save it in a syntfile.

To Paste Syntax from Dialog Boxes

E Open the dialog box and make the selections that you want.

E Click Paste.

The command syntax is pasted to the designated syntax window. If you do not hav

an open syntax window, a new syntax window opens automatically, and the syntax

pasted there.


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Chapter 12

Figure 12-1Command syntax pasted from a dialog box

Note: If you open a dialog box from the menus in a script window, code for running

syntax from a script is pasted into the script window.

CopyingSyntax from the Output Log

You can build a syntax file by copying command syntax from the log that appears in

the Viewer. To use this method, you must select Display commands in the log in theViewer settings (Edit menu, Options, Viewer tab) before running the analysis. Each

command will then appear in the Viewer along with the output from the analysis.

In the syntax window, you can run the pasted syntax, edit it, and save it in a syntax

file.


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Figure 12-2Command syntax in the log

To Copy Syntax from the Output Log

E Before running the analysis, from the menus choose:

EditOptions...


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Chapter 12

E On the Viewer tab, select Display commands in the log.

As you run analyses, the commands for your dialog box selections are recorded in

the log.

E Open a previously saved syntax file or create a new one. To create a new syntax

file, from the menus choose:

FileNew

Syntax

E In the Viewer, double-click on a log item to activate it.

E Click and drag the mouse to highlight the syntax that you want to copy.

E From the Viewer menus choose:

EditCopy

E In a syntax window, from the menus choose:

EditPaste

Editing Syntax in a Journal File

By default, all commands executed during a session are recorded in a journal file

named spss.jnl (set with Options on the Edit menu). You can edit the journal file and

save it as a syntax file that you can use to repeat a previously run analysis, or you can

run it in an automated job with the Production Facility.

The journal file is a text file that can be edited like any other text file. Because

error messages and warnings are also recorded in the journal file along with command

syntax, you must edit out any error and warning messages that appear before saving

the syntax file. Note, however, that errors must be resolved or the job will not run

successfully.

Save the edited journal file with a different filename. Because the journal file is

automatically appended or overwritten for each session, attempting to use the same

filename for a syntax file and the journal file may yield unexpected results.


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Figure 12-3Editing the journal file

Delete warnings anderror messagesbefore saving andrunning syntax fromthe journal file

To Edit Syntax in a Journal File

E To open the journal file, from the menus choose:

FileOpen

Other...

E Locate and open the journal file (by default, spss.jnl is located in the temp directory

Select All files (*.*) for Files of Type or enter *.jnl in the File Name text box to displa

journal files in the file list. If you have difficulty locating the file, use Options on th

Edit menu to see where the journal is saved in your system.

E Edit the file to remove any error messages or warnings, indicated by the > sign.

E Save the edited journal file using a different filename. (We recommend that you use

filename with the extension .sps, the default extension for syntax files.)

To Run Command Syntax

E Highlight the commands that you want to run in the syntax window.


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E Click the Run button (the right-pointing triangle) on the Syntax Editor toolbar.

or

E Select one of the choices from the Run menu.

All. Runs all commands in the syntax window.

Selection. Runs the currently selected commands. This includes any commands

partially highlighted.

Current. Runs the command where the cursor is currently located.

To End. Runs all commands from the current cursor location to the end of the

command syntax file.

The Run button on the Syntax Editor toolbar runs the selected commands or thecommand where the cursor is located if there is no selection.

Figure 12-4Syntax Editor toolbar

Multiple Execute Commands

Syntax pasted from dialog boxes or copied from the log or the journal may contain

EXECUTE commands. When you run multiple commands from a syntax window,

multiple EXECUTE commands are unnecessary and may slow performance because

this command reads the entire data file.

If the last command in the syntax file is a command that reads the data file (such

as a statistical or graphing procedure), no EXECUTE commands are necessary and

they can be deleted.

If you are unsure if the last command reads the data file, in most cases you can

delete all but the last EXECUTE command in the syntax file.


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Lag Functions

One notable exception is transformation commands that contain lag functions. In a

series of transformation commands without any intervening EXECUTE commands

or other commands that read the data, lag functions are calculated after all other

transformations, regardless of command order. For example:

COMPUTE lagvar=LAG(var1)

COMPUTE var1=var1*2

and

COMPUTE lagvar=LAG(var1)

EXECUTE

COMPUTE var1=var1*2

yield very different results for the value of lagvar, since the former uses the

transformed value ofvar1 while the latter uses the original value.

Documents

SPSS Usersguide12 Syntax