X-Git-Url: https://pintos-os.org/cgi-bin/gitweb.cgi?a=blobdiff_plain;f=doc%2Ffiles.texi;h=35bc7c98cfd07661aab65b8943dbdac89d440804;hb=577c6ac9b93c494efdabc324365ec70a43f6d742;hp=479fc0671960cd5a8fb82632239062053eaa7b17;hpb=72435b7315ecb4943d0c8cf4ffb04fbba695ca1d;p=pspp-builds.git diff --git a/doc/files.texi b/doc/files.texi index 479fc067..35bc7c98 100644 --- a/doc/files.texi +++ b/doc/files.texi @@ -1,4 +1,4 @@ -@node System and Portable Files, Variable Attributes, Data Input and Output, Top +@node System and Portable Files @chapter System Files and Portable Files The commands in this chapter read, write, and examine system files and @@ -195,12 +195,12 @@ extension. @display MATCH FILES /@{FILE,TABLE@}=@{*,'file-name'@} - /DROP=var_list - /KEEP=var_list /RENAME=(src_names=target_names)@dots{} /IN=var_name - /BY var_list + /BY=var_list + /DROP=var_list + /KEEP=var_list /FIRST=var_name /LAST=var_name /MAP @@ -208,38 +208,33 @@ MATCH FILES @cmd{MATCH FILES} merges one or more system, portable, or scratch files, optionally -including the active file. Records with the same values for BY -variables are combined into a single record. Records with different +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. -The BY subcommand specifies a list of variables that are used to match -records from each of the files. Variables specified must exist -in all the files specified on FILE and TABLE. BY should usually be -specified. If TABLE or IN is used then BY is required. - 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. Normally at least two FILE subcommands should be -specified. +BY is not specified. Specify TABLE with a file to use it as a @dfn{table -lookup file}. Records in table lookup files are not used up after +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 records in FILE files. Table lookup files +correspond to any number of cases in FILE files. Table lookup files correspond to lookup tables in traditional relational database systems. -It is incorrect to have records with duplicate BY values in table lookup -files. +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. Each -instance of FILE or TABLE can be followed by any sequence of DROP, -KEEP, or 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. +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 @@ -247,11 +242,38 @@ 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. -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. +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. -FIRST, LAST, and MAP are currently ignored. +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. @@ -378,7 +400,7 @@ the data is read by a procedure or procedure-like command. @xref{EXPORT}, for more information. -@node XSAVE, , XEXPORT, System and Portable Files +@node XSAVE @section XSAVE @vindex XSAVE