* 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.
+* Datasets:: Data organization.
* Files:: Files used by PSPP.
* File Handles:: How files are named.
* BNF:: How command syntax is described.
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.
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.
-
@cindex system file
@cindex file, system
@item system file
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{"}.
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
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},
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
projects / pspp-builds.git / blobdiff