@cindex cross-case function
@cindex function, cross-case
@deftypefn {Function} {} LAG (@var{variable})
+@anchor{LAG}
@var{variable} must be a numeric or string variable name. @code{LAG}
results in the value of that variable for the case before the current
one. In case-selection procedures, @code{LAG} results in the value of
variables are combined into a single record. Records with different
values are output in order. Thus, multiple sorted system files are
combined into a single sorted system file based on the value of the BY
-variables.
+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 system files. Variables specified must exist
IN, FIRST, LAST, and MAP are currently not used.
+@cmd{MATCH FILES} may not be specified following @cmd{TEMPORARY}
+(@pxref{TEMPORARY}) if the active file is used as an input source.
+
@node SAVE, SYSFILE INFO, MATCH FILES, System and Portable Files
@section SAVE
@vindex SAVE
If either DROP or KEEP is specified, the data is read; otherwise it is
not.
+@cmd{MODIFY VARS} may not be specified following @cmd{TEMPORARY}
+(@pxref{TEMPORARY}).
+
@node NUMERIC, PRINT FORMATS, MODIFY VARS, Variable Attributes
@section NUMERIC
@vindex NUMERIC
@cmd{RENAME VARIABLES} takes effect immediately. It does not cause the data
to be read.
+@cmd{RENAME VARIABLES} may not be specified following @cmd{TEMPORARY}
+(@pxref{TEMPORARY}).
+
@node VALUE LABELS, STRING, RENAME VARIABLES, Variable Attributes
@section VALUE LABELS
@vindex VALUE LABELS
(@pxref{LEAVE}) resets the variable's left state. Therefore,
@code{LEAVE} should be specified following @cmd{COMPUTE}, not before.
-COMPUTE is a transformation. It does not cause the active file to be
+@cmd{COMPUTE} is a transformation. It does not cause the active file to be
read.
+When @cmd{COMPUTE} is specified following @cmd{TEMPORARY}
+(@pxref{TEMPORARY}), the @cmd{LAG} function may not be used
+(@pxref{LAG}).
+
@node COUNT, FLIP, COMPUTE, Data Manipulation
@section COUNT
@vindex COUNT
variable can
be used to recreate the original variable names.
+FLIP honors N OF CASES. It ignores TEMPORARY, so that ``temporary''
+transformations become permanent.
+
@node IF, RECODE, FLIP, Data Manipulation
@section IF
@vindex IF
(@pxref{LEAVE}) resets the variable's left state. Therefore,
@code{LEAVE} should be specified following @cmd{IF}, not before.
+When @cmd{IF} is specified following @cmd{TEMPORARY}
+(@pxref{TEMPORARY}), the @cmd{LAG} function may not be used
+(@pxref{LAG}).
+
@node RECODE, SORT CASES, IF, Data Manipulation
@section RECODE
@vindex RECODE
@cmd{SORT CASES} attempts to sort the entire active file in main memory.
If main memory is exhausted, it falls back to a merge sort algorithm that
-involves writing and reading numerous temporary files. Environment
-variables determine the temporary files' location. The first of
-SPSSTMPDIR, SPSSXTMPDIR, or TMPDIR that is set determines the location.
-Otherwise, if the compiler environment defined P_tmpdir, that is used.
-Otherwise, under Unix-like OSes /tmp is used; under MS-DOS, the first of
-TEMP, TMP, or root on the current drive is used; under other OSes, the
-current directory.
+involves writing and reading numerous temporary files.
+
+@cmd{SORT CASES} may not be specified following TEMPORARY.
@node Data Selection, Conditionals and Looping, Data Manipulation, Top
@chapter Selecting data for analysis
BY is optional but recommended. Cases which have a zero or system- or
user-missing value are excluded from analysis, but not deleted from the
data stream. Cases with other values are analyzed.
+To filter based on a different condition, use
+transformations such as @cmd{COMPUTE} or @cmd{RECODE} to compute a
+filter variable of the required form, then specify that variable on
+@cmd{FILTER}.
@code{FILTER OFF} turns off case filtering.
Filtering takes place immediately before cases pass to a procedure for
analysis. Only one filter variable may be active at a time. Normally,
case filtering continues until it is explicitly turned off with @code{FILTER
-OFF}. However, if @cmd{FILTER} is placed after TEMPORARY, filtering stops
-after execution of the next procedure or procedure-like command.
+OFF}. However, if @cmd{FILTER} is placed after TEMPORARY, it filters only
+the next procedure or procedure-like command.
@node N OF CASES, PROCESS IF, FILTER, Data Selection
@section N OF CASES
processed by procedures. PSPP currently does not make use of
case count estimates.
+When @cmd{N} is specified after @cmd{TEMPORARY}, it affects only
+the next procedure (@pxref{TEMPORARY}).
+
@node PROCESS IF, SAMPLE, N OF CASES, Data Selection
@section PROCESS IF
@vindex PROCESS IF
effects of executing @cmd{TEMPORARY}, then @cmd{SELECT IF}
(@pxref{SELECT IF}).
+The filtering performed by @cmd{PROCESS IF} takes place immediately
+before cases pass to a procedure for analysis. Because @cmd{PROCESS
+IF} affects only a single procedure, its placement relative to
+@cmd{TEMPORARY} is unimportant.
+
@cmd{PROCESS IF} is deprecated. It is included for compatibility with
old command files. New syntax files should use @cmd{SELECT IF} or
@cmd{FILTER} instead.
SAMPLE num1 [FROM num2].
@end display
-@cmd{SAMPLE} is used to randomly sample a proportion of the cases in
-the active file. @cmd{SAMPLE} is temporary, affecting only the next
-procedure, unless that is a data transformation, such as @cmd{SELECT IF}
-or @cmd{RECODE}.
+@cmd{SAMPLE} randomly samples a proportion of the cases in the active
+file. Unless it follows @cmd{TEMPORARY}, it operates as a
+transformation, permanently removing cases from the active file.
The proportion to sample can be expressed as a single number between 0
and 1. If @code{k} is the number specified, and @code{N} is the number
@var{N} cases in the active file.}
@end enumerate
-@cmd{SAMPLE}, @cmd{SELECT IF}, and @code{PROCESS IF} are performed in
+@cmd{SAMPLE} and @cmd{SELECT IF} are performed in
the order specified by the syntax file.
-@cmd{SAMPLE} is ignored before @code{SORT CASES}.
-
@cmd{SAMPLE} is always performed before @code{N OF CASES}, regardless
-of ordering in the syntax file. @xref{N OF CASES}.
+of ordering in the syntax file (@pxref{N OF CASES}).
The same values for @cmd{SAMPLE} may result in different samples. To
obtain the same sample, use the @code{SET} command to set the random
possible. Cases that are deleted early can be processed more
efficiently in time and space.
+When @cmd{SELECT IF} is specified following @cmd{TEMPORARY}
+(@pxref{TEMPORARY}), the @cmd{LAG} function may not be used
+(@pxref{LAG}).
+
@node SPLIT FILE, TEMPORARY, SELECT IF, Data Selection
@section SPLIT FILE
@vindex SPLIT FILE
Specify OFF to disable @cmd{SPLIT FILE} and resume analysis of the
entire active file as a single group of data.
+When @cmd{SPLIT FILE} is specified after @cmd{TEMPORARY}, it affects only
+the next procedure (@pxref{TEMPORARY}).
+
@node TEMPORARY, WEIGHT, SPLIT FILE, Data Selection
@section TEMPORARY
@vindex TEMPORARY
affect only the execution of the next procedure or procedure-like
command. Their effects will not be saved to the active file.
-The only specification is the command name.
+The only specification on @cmd{TEMPORARY} is the command name.
@cmd{TEMPORARY} may not appear within a @cmd{DO IF} or @cmd{LOOP}
-construct. It may
-appear only once between procedures and procedure-like commands.
+construct. It may appear only once between procedures and
+procedure-like commands.
+
+Scratch variables cannot be used following @cmd{TEMPORARY}.
An example may help to clarify:
variable are interpreted as weighting factors of 0. User-missing
values are not treated specially.
+When @cmd{WEIGHT} is specified after @cmd{TEMPORARY}, it affects only
+the next procedure (@pxref{TEMPORARY}).
+
@cmd{WEIGHT} does not cause cases in the active file to be replicated in
memory.
turn, with the same rules applied. If all expressions evaluate to
false, then the @cmd{ELSE} code block is executed, if it is present.
+When @cmd{DO IF} or @cmd{ELSE IF} is specified following @cmd{TEMPORARY}
+(@pxref{TEMPORARY}), the @cmd{LAG} function may not be used
+(@pxref{LAG}).
+
@node DO REPEAT, LOOP, DO IF, Conditionals and Looping
@section DO REPEAT
@vindex DO REPEAT
@cmd{BREAK} also terminates @cmd{LOOP} execution (@pxref{BREAK}).
+When @cmd{LOOP} or @cmd{END LOOP} is specified following @cmd{TEMPORARY}
+(@pxref{TEMPORARY}), the @cmd{LAG} function may not be used
+(@pxref{LAG}).
+
@node Statistics, Utilities, Conditionals and Looping, Top
@chapter Statistics
The @cmd{MISSING} subcommand determines the handling of missing
variables.
If INCLUDE is set, then user-missing values are included in the
-calculations.
+calculations, but system-missing values are not.
If EXCLUDE is set, which is the default, user-missing
-values are excluded.
-If LISTWISE is set, then
-the entire case is excluded whenever any value in that case has a
-system-missing or, if INCLUDE is set, user-missing value.
-If ANALYSIS is set, then cases are excluded only where a value used in
-the analysis has a system-missing or, if INCLUDE is set, user-missing value.
+values are excluded as well as system-missing values.
+This is the default.
+
+If LISTWISE is set, then the entire case is excluded from analysis
+whenever any variable specified in the @cmd{/VARIABLES}, @cmd{/PAIRS} or
+@cmd{/GROUPS} subcommands contains a missing value.
+If ANALYSIS is set, then missing values are excluded only in the analysis for
+which they would be needed. This is the default.
@menu
variable which determines to which group the samples belong.
The values in parentheses are the specific values of the independent
variable for each group.
-If the parentheses are omitted, and no values are given, the default values
+If the parentheses are omitted and no values are given, the default values
of 1.0 and 2.0 are assumed.
-If only one value is given, then cases where the independent variable is
+
+If the independent variable is numeric,
+it is acceptable to specify only one value inside the parentheses.
+If you do this, cases where the independent variable is
less than or equal to this value belong to the first group, and cases
greater than this value belong to the second group.
-If only one value is given, then the independent variable must be
-numeric.
+When using this form of the @cmd{GROUPS} subcommand, missing values in
+the independent variable are excluded on a listwise basis, regardless
+of whether @cmd{/MISSING=LISTWISE} was specified.
@node Paired Samples Mode, , Independent Samples Mode, T-TEST
projects / pspp / blobdiff