docs

[pspp] / doc / data-selection.texi

diff --git a/doc/data-selection.texi b/doc/data-selection.texi
index 71b4e3de5aa45a8b4c72a67ff8725157446731f4..c2f3ab31a4ddf0fdd33797a83981acd820e35590 100644 (file)
--- a/doc/data-selection.texi
+++ b/doc/data-selection.texi
@@ -156,11 +156,38 @@ deleted from the data stream.
 Place @cmd{SELECT IF} as early in the command file as
 possible.  Cases that are deleted early can be processed more
 efficiently in time and space.
+Once cases have been deleted from the active dataset using @cmd{SELECT IF} they
+cannot be re-instated.
+If you want to be able to re-instate cases, then use @cmd{FILTER} (@pxref{FILTER})
+instead.
 
 When @cmd{SELECT IF} is specified following @cmd{TEMPORARY}
 (@pxref{TEMPORARY}), the @cmd{LAG} function may not be used
 (@pxref{LAG}).
 
+@subsection Example Select-If
+
+A shop steward is interested in the salaries of younger personnel in a firm.
+The file @file{personnel.sav} provides the salaries of all the workers and their
+dates of birth.  The syntax in @ref{select-if:ex} shows how @cmd{SELECT IF} can
+be used to limit analysis only to those persons born after December 31, 1999.
+
+@float Example, select-if:ex
+@psppsyntax {select-if.sps}
+@caption {Using @cmd{SELECT IF} to select persons born on or after a certain date.}
+@end float
+
+From @ref{select-if:res} one can see that there are 56 persons listed in the dataset,
+and 17 of them were born after December 31, 1999.
+
+@float Result, select-if:res
+@psppoutput {select-if}
+@caption {Salary descriptives before and after the @cmd{SELECT IF} transformation.}
+@end float
+
+Note that the @file{personnel.sav} file from which the data were read is unaffected.
+The transformation affects only the active file.
+
 @node SPLIT FILE
 @section SPLIT FILE
 @vindex SPLIT FILE
@@ -227,6 +254,17 @@ split.
 
 Unless @cmd{TEMPORARY} was used, after a split has been defined for
 a dataset it remains active until explicitly disabled.
+In the graphical user interface, the active split variable (if any) is
+displayed in the status bar (@pxref{split-status-bar:scr}.
+If a dataset is saved to a system file (@pxref{SAVE}) whilst a split
+is active, the split stastus is stored in the file and will be
+automatically loaded when that file is loaded.
+
+@float Screenshot, split-status-bar:scr
+@psppimage {split-status-bar}
+@caption {The status bar indicating that the data set is split using the @exvar{treatment} variable}
+@end float
+
 
 @node TEMPORARY
 @section TEMPORARY
@@ -249,31 +287,30 @@ procedure-like commands.
 
 Scratch variables cannot be used following @cmd{TEMPORARY}.
 
-An example may help to clarify:
+@subsection Example Temporary
 
-@example
-DATA LIST /X 1-2.
-BEGIN DATA.
- 2
- 4
-10
-15
-20
-24
-END DATA.
+In @ref{temporary:ex} there are two @cmd{COMPUTE} transformation.  One
+of them immediatly follows a @cmd{TEMPORARY} command, and therefore has
+effect only for the next procedure, which in this case is the first
+@cmd{DESCRIPTIVES} command.
 
-COMPUTE X=X/2.
+@float Example, temporary:ex
+@psppsyntax {temporary.sps}
+@caption {Running a @cmd{COMPUTE} transformation after @cmd{TEMPORARY}}
+@end float
 
-TEMPORARY.
-COMPUTE X=X+3.
+The data read by the first @cmd{DESCRIPTIVES} procedure are 4, 5, 8,
+10.5, 13, 15.  The data read by the second @cmd{DESCRIPTIVES} procedure are 1, 2,
+5, 7.5, 10, 12.   This is because the second @cmd{COMPUTE} transformation
+has no effect on the second @cmd{DESCRIPTIVES} procedure.   You can check these
+figures in @ref{temporary:res}.
 
-DESCRIPTIVES X.
-DESCRIPTIVES X.
-@end example
+@float Result, temporary:res
+@psppoutput {temporary}
+@caption {The results of running two consecutive @cmd{DESCRIPTIVES} commands after
+         a temporary transformation}
+@end float
 
-The data read by the first @cmd{DESCRIPTIVES} are 4, 5, 8,
-10.5, 13, 15.  The data read by the first @cmd{DESCRIPTIVES} are 1, 2,
-5, 7.5, 10, 12.
 
 @node WEIGHT
 @section WEIGHT