-@node System and Portable Files
-@chapter System Files and Portable Files
+@node System and Portable File IO
+@chapter System and Portable File I/O
The commands in this chapter read, write, and examine system files and
portable files.
* GET:: Read from a system file.
* GET DATA:: Read from foreign files.
* IMPORT:: Read from a portable file.
-* MATCH FILES:: Merge system files.
* SAVE:: Write to a system file.
* SYSFILE INFO:: Display system file dictionary.
* XEXPORT:: Write to a portable file, as a transformation.
Use of @cmd{IMPORT} to read a system file or scratch file is a PSPP
extension.
-@node MATCH FILES
-@section MATCH FILES
-@vindex MATCH FILES
-
-@display
-MATCH FILES
- /@{FILE,TABLE@}=@{*,'file-name'@}
- /RENAME=(src_names=target_names)@dots{}
- /IN=var_name
-
- /BY=var_list
- /DROP=var_list
- /KEEP=var_list
- /FIRST=var_name
- /LAST=var_name
- /MAP
-@end display
-
-@cmd{MATCH FILES} merges one or more system, portable, or scratch files,
-optionally
-including the active file. Cases with the same values for BY
-variables are combined into a single case. Cases with different
-values are output in order. Thus, multiple sorted files are
-combined into a single sorted file based on the value of the BY
-variables. The results of the merge become the new active file.
-
-Specify FILE with a system, portable, or scratch file as a file name
-string or file handle
-(@pxref{File Handles}), or with an asterisk (@samp{*}) to
-indicate the current active file. The files specified on FILE are
-merged together based on the BY variables, or combined case-by-case if
-BY is not specified.
-
-Specify TABLE with a file to use it as a @dfn{table
-lookup file}. Cases in table lookup files are not used up after
-they've been used once. This means that data in table lookup files can
-correspond to any number of cases in FILE files. Table lookup files
-correspond to lookup tables in traditional relational database systems.
-If a table lookup file contains more than one case with a given set of
-BY variables, only the first case is used.
-
-Any number of FILE and TABLE subcommands may be specified.
-Ordinarily, at least two FILE subcommands, or one FILE and at least
-one TABLE, should be specified. Each instance of FILE or TABLE can be
-followed by any sequence of RENAME subcommands. These have the same
-form and meaning as the corresponding subcommands of @cmd{GET}
-(@pxref{GET}), but apply only to variables in the given file.
-
-Each FILE or TABLE may optionally be followed by an IN subcommand,
-which creates a numeric variable with the specified name and format
-F1.0. The IN variable takes value 1 in a case if the given file
-contributed a row to the merged file, 0 otherwise. The DROP, KEEP,
-and RENAME subcommands do not affect IN variables.
-
-When more than one FILE or TABLE contains a variable with a given
-name, those variables must all have the same type (numeric or string)
-and, for string variables, the same width. This rules applies to
-variable names after renaming with RENAME; thus, RENAME can be used to
-resolve conflicts.
-
-FILE and TABLE must be specified at the beginning of the command, with
-any RENAME or IN specifications immediately after the corresponding
-FILE or TABLE. These subcommands are followed by BY, DROP, KEEP,
-FIRST, LAST, and MAP.
-
-The BY subcommand specifies a list of variables that are used to match
-cases from each of the files. When TABLE or IN is used, BY is
-required; otherwise, it is optional. When BY is specified, all the
-files named on FILE and TABLE subcommands must be sorted in ascending
-order of the BY variables. Variables belonging to files that are not
-present for the current case are set to the system-missing value for
-numeric variables or spaces for string variables.
-
-The DROP and KEEP subcommands allow variables to be dropped from or
-reordered within the new active file. These subcommands have the same
-form and meaning as the corresponding subcommands of @cmd{GET}
-(@pxref{GET}). They apply to the new active file as a whole, not to
-individual input files. The variable names specified on DROP and KEEP
-are those after any renaming with RENAME.
-
-The optional FIRST and LAST subcommands name variables that @cmd{MATCH
-FILES} adds to the active file. The new variables are numeric with
-print and write format F1.0. The value of the FIRST variable is 1 in
-the first case with a given set of values for the BY variables, and 0
-in other cases. Similarly, the LAST variable is 1 in the last case
-with a given of BY values, and 0 in other cases.
-
-@cmd{MATCH FILES} may not be specified following @cmd{TEMPORARY}
-(@pxref{TEMPORARY}) if the active file is used as an input source.
-
-Use of portable or scratch files on @cmd{MATCH FILES} is a PSPP
-extension.
-
@node SAVE
@section SAVE
@vindex SAVE
projects / pspp-builds.git / blobdiff