@node Language
-@chapter The PSPP language
-@cindex language, PSPP
-@cindex PSPP, language
+@chapter The @pspp{} language
+@cindex language, @pspp{}
+@cindex @pspp{}, language
-@note{PSPP is not even close to completion.
-Only a few statistical procedures are implemented. PSPP
-is a work in progress.}
-
-This chapter discusses elements common to many PSPP commands.
+This chapter discusses elements common to many @pspp{} commands.
Later chapters will describe individual commands in detail.
@menu
* Types of Commands:: Commands come in several flavors.
* Order of Commands:: Commands combine to form syntax files.
* Missing Observations:: Handling missing observations.
-* Variables:: The unit of data storage.
-* Files:: Files used by PSPP.
+* Datasets:: Data organization.
+* Files:: Files used by @pspp{}.
* File Handles:: How files are named.
* BNF:: How command syntax is described.
@end menu
@cindex tokens
@cindex lexical analysis
-PSPP divides most syntax file lines into series of short chunks
+@pspp{} divides most syntax file lines into series of short chunks
called @dfn{tokens}.
Tokens are then grouped to form commands, each of which tells
-PSPP to take some action---read in data, write out data, perform
+@pspp{} to take some action---read in data, write out data, perform
a statistical procedure, etc. Each type of token is
described below.
significant inside strings.
Strings can be concatenated using @samp{+}, so that @samp{"a" + 'b' +
-'c'} is equivalent to @samp{'abc'}. Concatenation is useful for
-splitting a single string across multiple source lines. The maximum
-length of a string, after concatenation, is 255 characters.
-
-Strings may also be expressed as hexadecimal, octal, or binary
-character values by prefixing the initial quote character by @samp{X},
-@samp{O}, or @samp{B} or their lowercase equivalents. Each pair,
-triplet, or octet of characters, according to the radix, is
-transformed into a single character with the given value. If there is
-an incomplete group of characters, the missing final digits are
-assumed to be @samp{0}. These forms of strings are nonportable
-because numeric values are associated with different characters by
-different operating systems. Therefore, their use should be confined
-to syntax files that will not be widely distributed.
-
-@cindex characters, reserved
-@cindex 0
-@cindex white space
-The character with value 00 is reserved for
-internal use by PSPP. Its use in strings causes an error and
-replacement by a space character.
+'c'} is equivalent to @samp{'abc'}. So that a long string may be
+broken across lines, a line break may precede or follow, or both
+precede and follow, the @samp{+}. (However, an entirely blank line
+preceding or following the @samp{+} is interpreted as ending the
+current command.)
+
+Strings may also be expressed as hexadecimal character values by
+prefixing the initial quote character by @samp{x} or @samp{X}.
+Regardless of the syntax file or active dataset's encoding, the
+hexadecimal digits in the string are interpreted as Unicode characters
+in UTF-8 encoding.
+
+Individual Unicode code points may also be expressed by specifying the
+hexadecimal code point number in single or double quotes preceded by
+@samp{u} or @samp{U}. For example, Unicode code point U+1D11E, the
+musical G clef character, could be expressed as @code{U'1D11E'}.
+Invalid Unicode code points (above U+10FFFF or in between U+D800 and
+U+DFFF) are not allowed.
+
+When strings are concatenated with @samp{+}, each segment's prefix is
+considered individually. For example, @code{'The G clef symbol is:' +
+u"1d11e" + "."} inserts a G clef symbol in the middle of an otherwise
+plain text string.
@item Punctuators and Operators
@cindex punctuators
When it is the last non-space character on a line, a period is not
treated as part of another token, even if it would otherwise be part
of, e.g.@:, an identifier or a floating-point number.
-
-Actually, the character that ends a command can be changed with
-@cmd{SET}'s ENDCMD subcommand (@pxref{SET}), but we do not recommend
-doing so. Throughout the remainder of this manual we will assume that
-the default setting is in effect.
@end table
@node Commands
@section Forming commands of tokens
-@cindex PSPP, command structure
+@cindex @pspp{}, command structure
@cindex language, command structure
@cindex commands, structure
-Most PSPP commands share a common structure. A command begins with a
+Most @pspp{} commands share a common structure. A command begins with a
command name, such as @cmd{FREQUENCIES}, @cmd{DATA LIST}, or @cmd{N OF
CASES}. The command name may be abbreviated to its first word, and
each word in the command name may be abbreviated to its first three
There are multiple ways to mark the end of a command. The most common
way is to end the last line of the command with a period (@samp{.}) as
described in the previous section (@pxref{Tokens}). A blank line, or
-one that consists only of white space or comments, also ends a command
-by default, although you can use the NULLINE subcommand of @cmd{SET}
-to disable this feature (@pxref{SET}).
+one that consists only of white space or comments, also ends a command.
@node Syntax Variants
-@section Variants of syntax.
+@section Syntax Variants
@cindex Batch syntax
@cindex Interactive syntax
-There are two variants of command syntax, @i{viz}: @dfn{batch} mode and
-@dfn{interactive} mode.
-Batch mode is the default when reading commands from a file.
-Interactive mode is the default when commands are typed at a prompt
-by a user.
-Certain commands, such as @cmd{INSERT} (@pxref{INSERT}), may explicitly
-change the syntax mode.
-
-In batch mode, any line that contains a non-space character
-in the leftmost column begins a new command.
-Thus, each command consists of a flush-left line followed by any
-number of lines indented from the left margin.
-In this mode, a plus or minus sign (@samp{+}, @samp{@minus{}}) as the
-first character in a line is ignored and causes that line to begin a
-new command, which allows for visual indentation of a command without
-that command being considered part of the previous command.
-The period terminating the end of a command is optional but recommended.
-
-In interactive mode, each command must either be terminated with a period,
-or an empty line must follow the command.
-The use of (@samp{+} and @samp{@minus{}} as continuation characters is not
-permitted.
+There are three variants of command syntax, which vary only in how
+they detect the end of one command and the start of the next.
+
+In @dfn{interactive mode}, which is the default for syntax typed at a
+command prompt, a period as the last non-blank character on a line
+ends a command. A blank line also ends a command.
+
+In @dfn{batch mode}, an end-of-line period or a blank line also ends a
+command. Additionally, it treats any line that has a non-blank
+character in the leftmost column as beginning a new command. Thus, in
+batch mode the second and subsequent lines in a command must be
+indented.
+
+Regardless of the syntax mode, a plus sign, minus sign, or period in
+the leftmost column of a line is ignored and causes that line to begin
+a new command. This is most useful in batch mode, in which the first
+line of a new command could not otherwise be indented, but it is
+accepted regardless of syntax mode.
+
+The default mode for reading commands from a file is @dfn{auto mode}.
+It is the same as batch mode, except that a line with a non-blank in
+the leftmost column only starts a new command if that line begins with
+the name of a @pspp{} command. This correctly interprets most valid @pspp{}
+syntax files regardless of the syntax mode for which they are
+intended.
+
+The @option{--interactive} (or @option{-i}) or @option{--batch} (or
+@option{-b}) options set the syntax mode for files listed on the @pspp{}
+command line. @xref{Main Options}, for more details.
@node Types of Commands
@section Types of Commands
-Commands in PSPP are divided roughly into six categories:
+Commands in @pspp{} are divided roughly into six categories:
@table @strong
@item Utility commands
@cindex utility commands
-Set or display various global options that affect PSPP operations.
+Set or display various global options that affect @pspp{} operations.
May appear anywhere in a syntax file. @xref{Utilities, , Utility
commands}.
Analyze data, writing results of analyses to the listing file. Cause
transformations specified earlier in the file to be performed. In a
more general sense, a @dfn{procedure} is any command that causes the
-active file (the data) to be read.
+active dataset (the data) to be read.
@end table
@node Order of Commands
@cindex commands, ordering
@cindex order of commands
-PSPP does not place many restrictions on ordering of commands. The
+@pspp{} does not place many restrictions on ordering of commands. The
main restriction is that variables must be defined before they are otherwise
referenced. This section describes the details of command ordering,
but most users will have no need to refer to them.
-PSPP possesses five internal states, called initial, INPUT PROGRAM,
-FILE TYPE, transformation, and procedure states. (Please note the
+@pspp{} possesses five internal states, called @dfn{initial}, @dfn{input-program}
+@dfn{file-type}, @dfn{transformation}, and @dfn{procedure} states. (Please note the
distinction between the @cmd{INPUT PROGRAM} and @cmd{FILE TYPE}
-@emph{commands} and the INPUT PROGRAM and FILE TYPE @emph{states}.)
+@emph{commands} and the @dfn{input-program} and @dfn{file-type} @emph{states}.)
-PSPP starts in the initial state. Each successful completion
+@pspp{} starts in the initial state. Each successful completion
of a command may cause a state transition. Each type of command has its
own rules for state transitions:
When executed in the initial or procedure state, causes a transition to
the transformation state.
@item
-Clears the active file if executed in the procedure or transformation
+Clears the active dataset if executed in the procedure or transformation
state.
@end itemize
@item @cmd{INPUT PROGRAM}
@itemize @bullet
@item
-Invalid in INPUT PROGRAM and FILE TYPE states.
+Invalid in input-program and file-type states.
@item
-Causes a transition to the INPUT PROGRAM state.
+Causes a transition to the intput-program state.
@item
-Clears the active file.
+Clears the active dataset.
@end itemize
@item @cmd{FILE TYPE}
@itemize @bullet
@item
-Invalid in INPUT PROGRAM and FILE TYPE states.
+Invalid in intput-program and file-type states.
@item
-Causes a transition to the FILE TYPE state.
+Causes a transition to the file-type state.
@item
-Clears the active file.
+Clears the active dataset.
@end itemize
@item Other file definition commands
@itemize @bullet
@item
-Invalid in INPUT PROGRAM and FILE TYPE states.
+Invalid in input-program and file-type states.
@item
Cause a transition to the transformation state.
@item
-Clear the active file, except for @cmd{ADD FILES}, @cmd{MATCH FILES},
+Clear the active dataset, except for @cmd{ADD FILES}, @cmd{MATCH FILES},
and @cmd{UPDATE}.
@end itemize
@item Transformations
@itemize @bullet
@item
-Invalid in initial and FILE TYPE states.
+Invalid in initial and file-type states.
@item
Cause a transition to the transformation state.
@end itemize
@item Restricted transformations
@itemize @bullet
@item
-Invalid in initial, INPUT PROGRAM, and FILE TYPE states.
+Invalid in initial, input-program, and file-type states.
@item
Cause a transition to the transformation state.
@end itemize
@item Procedures
@itemize @bullet
@item
-Invalid in initial, INPUT PROGRAM, and FILE TYPE states.
+Invalid in initial, input-program, and file-type states.
@item
Cause a transition to the procedure state.
@end itemize
@cindex missing values
@cindex values, missing
-PSPP includes special support for unknown numeric data values.
+@pspp{} includes special support for unknown numeric data values.
Missing observations are assigned a special value, called the
@dfn{system-missing value}. This ``value'' actually indicates the
absence of a value; it means that the actual value is unknown. Procedures
treated in the same way as the system-missing value.
For more information on missing values, see the following sections:
-@ref{Variables}, @ref{MISSING VALUES}, @ref{Expressions}. See also the
+@ref{Datasets}, @ref{MISSING VALUES}, @ref{Expressions}. See also the
documentation on individual procedures for information on how they
handle missing values.
-@node Variables
-@section Variables
-@cindex variables
+@node Datasets
+@section Datasets
+@cindex dataset
+@cindex variable
@cindex dictionary
-Variables are the basic unit of data storage in PSPP. All the
-variables in a file taken together, apart from any associated data, are
-said to form a @dfn{dictionary}.
-Some details of variables are described in the sections below.
+@pspp{} works with data organized into @dfn{datasets}. A dataset
+consists of a set of @dfn{variables}, which taken together are said to
+form a @dfn{dictionary}, and one or more @dfn{cases}, each of which
+has one value for each variable.
+
+At any given time @pspp{} has exactly one distinguished dataset, called
+the @dfn{active dataset}. Most @pspp{} commands work only with the
+active dataset. In addition to the active dataset, @pspp{} also supports
+any number of additional open datasets. The @cmd{DATASET} commands
+can choose a new active dataset from among those that are open, as
+well as create and destroy datasets (@pxref{DATASET}).
+
+The sections below describe variables in more detail.
@menu
* Attributes:: Attributes of variables.
-* System Variables:: Variables automatically defined by PSPP.
+* System Variables:: Variables automatically defined by @pspp{}.
* Sets of Variables:: Lists of variable names.
* Input and Output Formats:: Input and output formats.
* Scratch Variables:: Variables deleted by procedures.
@cindex @samp{_}
The final character in a variable name should not be @samp{_}, because
-some such identifiers are used for special purposes by PSPP
+some such identifiers are used for special purposes by @pspp{}
procedures.
-As with all PSPP identifiers, variable names are not case-sensitive.
-PSPP capitalizes variable names on output the same way they were
+As with all @pspp{} identifiers, variable names are not case-sensitive.
+@pspp{} capitalizes variable names on output the same way they were
capitalized at their point of definition in the input.
@cindex variables, type
@end table
@node System Variables
-@subsection Variables Automatically Defined by PSPP
+@subsection Variables Automatically Defined by @pspp{}
@cindex system variables
@cindex variables, system
@cindex @code{$DATE}
@item $DATE
-Date the PSPP process was started, in format A9, following the
+Date the @pspp{} process was started, in format A9, following the
pattern @code{DD MMM YY}.
@cindex @code{$JDATE}
@item $JDATE
-Number of days between 15 Oct 1582 and the time the PSPP process
+Number of days between 15 Oct 1582 and the time the @pspp{} process
was started.
@cindex @code{$LENGTH}
@cindex @code{$TIME}
@item $TIME
-Number of seconds between midnight 14 Oct 1582 and the time the active file
+Number of seconds between midnight 14 Oct 1582 and the time the active dataset
was read, in format F20.
@cindex @code{$WIDTH}
contains an ordinary decimal number, a time or date, a number in binary
or hexadecimal notation, or one of several other notations. Input
formats are used by commands such as @cmd{DATA LIST} that read data or
-syntax files into the PSPP active file.
+syntax files into the @pspp{} active dataset.
Every input format corresponds to a default @dfn{output format} that
specifies the formatting used when the value is output later. It is
most of the time, the distinction between print and write formats is
unimportant.
-Input and output formats are specified to PSPP with a @dfn{format
-specification} of the form @code{TYPEw} or @code{TYPEw.d}, where
-@code{TYPE} is one of the format types described later, @code{w} is a
-field width measured in columns, and @code{d} is an optional number of
-decimal places. If @code{d} is omitted, a value of 0 is assumed. Some
-formats do not allow a nonzero @code{d} to be specified.
+Input and output formats are specified to @pspp{} with
+a @dfn{format specification} of the
+form @subcmd{@var{TYPE}@var{w}} or @code{TYPE@var{w}.@var{d}}, where
+@var{TYPE} is one of the format types described later, @var{w} is a
+field width measured in columns, and @var{d} is an optional number of
+decimal places. If @var{d} is omitted, a value of 0 is assumed. Some
+formats do not allow a nonzero @var{d} to be specified.
The following sections describe the input and output formats supported
-by PSPP.
+by @pspp{}.
@menu
* Basic Numeric Formats::
Other than the hexadecimal representation, these formats are equivalent
to PIB and RB formats, respectively. However, bytes in PIBHEX format
are always ordered with the most-significant byte first (big-endian
-order), regardless of the host machine's native byte order or PSPP
+order), regardless of the host machine's native byte order or @pspp{}
settings.
Field widths must be even and between 2 and 16. RBHEX format allows no
@cindex time formats
@cindex date formats
-In PSPP, a @dfn{time} is an interval. The time formats translate
-between human-friendly descriptions of time intervals and PSPP's
+In @pspp{}, a @dfn{time} is an interval. The time formats translate
+between human-friendly descriptions of time intervals and @pspp{}'s
internal representation of time intervals, which is simply the number of
-seconds in the interval. PSPP has two time formats:
+seconds in the interval. @pspp{} has two time formats:
@float
@multitable {Time Format} {@code{dd-mmm-yyyy HH:MM:SS.ss}} {@code{01-OCT-1978 04:31:17.01}}
@end multitable
@end float
-A @dfn{date} is a moment in the past or the future. Internally, PSPP
+A @dfn{date} is a moment in the past or the future. Internally, @pspp{}
represents a date as the number of seconds since the @dfn{epoch},
midnight, Oct. 14, 1582. The date formats translate between
-human-readable dates and PSPP's numeric representation of dates and
-times. PSPP has several date formats:
+human-readable dates and @pspp{}'s numeric representation of dates and
+times. @pspp{} has several date formats:
@float
@multitable {Date Format} {@code{dd-mmm-yyyy HH:MM:SS.ss}} {@code{01-OCT-1978 04:31:17.01}}
@end table
For the time and date formats, the default output format is the same as
-the input format, except that PSPP increases the field width, if
+the input format, except that @pspp{} increases the field width, if
necessary, to the minimum allowed for output.
Time or dates narrower than the field width are right-justified within
@cindex scratch variables
Most of the time, variables don't retain their values between cases.
-Instead, either they're being read from a data file or the active file,
+Instead, either they're being read from a data file or the active dataset,
in which case they assume the value read, or, if created with
@cmd{COMPUTE} or
another transformation, they're initialized to the system-missing value
variable in the analysis.
@node Files
-@section Files Used by PSPP
+@section Files Used by @pspp{}
-PSPP makes use of many files each time it runs. Some of these it
+@pspp{} makes use of many files each time it runs. Some of these it
reads, some it writes, some it creates. Here is a table listing the
most important of these files:
@item command file
@itemx syntax file
These names (synonyms) refer to the file that contains instructions
-that tell PSPP what to do. The syntax file's name is specified on
-the PSPP command line. Syntax files can also be read with
+that tell @pspp{} what to do. The syntax file's name is specified on
+the @pspp{} command line. Syntax files can also be read with
@cmd{INCLUDE} (@pxref{INCLUDE}).
@cindex file, data
@cindex file, output
@cindex output file
@item listing file
-One or more output files are created by PSPP each time it is
+One or more output files are created by @pspp{} each time it is
run. The output files receive the tables and charts produced by
statistical procedures. The output files may be in any number of formats,
-depending on how PSPP is configured.
-
-@cindex active file
-@cindex file, active
-@item active file
-The active file is the ``file'' on which all PSPP procedures are
-performed. The active file consists of a dictionary and a set of cases.
-The active file is not necessarily a disk file: it is stored in memory
-if there is room.
+depending on how @pspp{} is configured.
@cindex system file
@cindex file, system
Portable files are files in a text-based format that store a dictionary
and a set of cases. @cmd{IMPORT} and @cmd{EXPORT} read and write
portable files.
-
-@cindex scratch file
-@cindex file, scratch
-@item scratch file
-Scratch files consist of a dictionary and cases and may be stored in
-memory or on disk. Most procedures that act on a system file or
-portable file can use a scratch file instead. The contents of scratch
-files persist within a single PSPP session only. @cmd{GET} and
-@cmd{SAVE} can be used to read and write scratch files. Scratch files
-are a PSPP extension.
@end table
@node File Handles
@section File Handles
@cindex file handles
-A @dfn{file handle} is a reference to a data file, system file, portable
-file, or scratch file. Most often, a file handle is specified as the
+A @dfn{file handle} is a reference to a data file, system file, or
+portable file. Most often, a file handle is specified as the
name of a file as a string, that is, enclosed within @samp{'} or
@samp{"}.
(e.g.@: @code{GET '|zcat mydata.sav.gz'}), and for many other
purposes.
-PSPP also supports declaring named file handles with the @cmd{FILE
+@pspp{} also supports declaring named file handles with the @cmd{FILE
HANDLE} command. This command associates an identifier of your choice
(the file handle's name) with a file. Later, the file handle name can
-be substituted for the name of the file. When PSPP syntax accesses a
+be substituted for the name of the file. When @pspp{} syntax accesses a
file multiple times, declaring a named file handle simplifies updating
the syntax later to use a different file. Use of @cmd{FILE HANDLE} is
also required to read data files in binary formats. @xref{FILE HANDLE},
for more information.
-PSPP assumes that a file handle name that begins with @samp{#} refers to
-a scratch file, unless the name has already been declared on @cmd{FILE
-HANDLE} to refer to another kind of file. A scratch file is similar to
-a system file, except that it persists only for the duration of a given
-PSPP session. Most commands that read or write a system or portable
-file, such as @cmd{GET} and @cmd{SAVE}, also accept scratch file
-handles. Scratch file handles may also be declared explicitly with
-@cmd{FILE HANDLE}. Scratch files are a PSPP extension.
-
-In some circumstances, PSPP must distinguish whether a file handle
+In some circumstances, @pspp{} must distinguish whether a file handle
refers to a system file or a portable file. When this is necessary to
read a file, e.g.@: as an input file for @cmd{GET} or @cmd{MATCH FILES},
-PSPP uses the file's contents to decide. In the context of writing a
-file, e.g.@: as an output file for @cmd{SAVE} or @cmd{AGGREGATE}, PSPP
+@pspp{} uses the file's contents to decide. In the context of writing a
+file, e.g.@: as an output file for @cmd{SAVE} or @cmd{AGGREGATE}, @pspp{}
decides based on the file's name: if it ends in @samp{.por} (with any
-capitalization), then PSPP writes a portable file; otherwise, PSPP
+capitalization), then @pspp{} writes a portable file; otherwise, @pspp{}
writes a system file.
INLINE is reserved as a file handle name. It refers to the ``data
The file to which a file handle refers may be reassigned on a later
@cmd{FILE HANDLE} command if it is first closed using @cmd{CLOSE FILE
-HANDLE}. The @cmd{CLOSE FILE HANDLE} command is also useful to free the
-storage associated with a scratch file. @xref{CLOSE FILE HANDLE}, for
+HANDLE}. @xref{CLOSE FILE HANDLE}, for
more information.
@node BNF
@cindex command syntax, description of
@cindex description of command syntax
-The syntax of some parts of the PSPP language is presented in this
+The syntax of some parts of the @pspp{} language is presented in this
manual using the formalism known as @dfn{Backus-Naur Form}, or BNF. The
following table describes BNF:
@cindex keywords
@cindex terminals
@item
-Words in all-uppercase are PSPP keyword tokens. In BNF, these are
+Words in all-uppercase are @pspp{} keyword tokens. In BNF, these are
often called @dfn{terminals}. There are some special terminals, which
are written in lowercase for clarity:
projects / pspp / blobdiff