AUTORECODE: Properly handle value labels.

[pspp] / doc / transformation.texi

diff --git a/doc/transformation.texi b/doc/transformation.texi
index 1ca2d22b297ba0727c1d089532ad3ac9312a14f4..01d26621d4f8d0febaa5422ea7736bce0943135d 100644 (file)
--- a/doc/transformation.texi
+++ b/doc/transformation.texi
@@ -1,3 +1,12 @@
+@c PSPP - a program for statistical analysis.
+@c Copyright (C) 2017 Free Software Foundation, Inc.
+@c Permission is granted to copy, distribute and/or modify this document
+@c under the terms of the GNU Free Documentation License, Version 1.3
+@c or any later version published by the Free Software Foundation;
+@c with no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts.
+@c A copy of the license is included in the section entitled "GNU
+@c Free Documentation License".
+@c
 @node Data Manipulation
 @chapter Data transformations
 @cindex transformations
@@ -238,17 +247,37 @@ variables, @subcmd{INTO}, and a list of target variables.  There must the same
 number of source and target variables.  The target variables must not
 already exist.
 
-By default, increasing values of a source variable (for a string, this
-is based on character code comparisons) are recoded to increasing values
-of its target variable.  To cause increasing values of a source variable
-to be recoded to decreasing values of its target variable (@var{n} down
-to 1), specify @subcmd{DESCENDING}.
+@cmd{AUTORECODE} ordinarily assigns each increasing non-missing value
+of a source variable (for a string, this is based on character code
+comparisons) to consecutive values of its target variable.  For
+example, the smallest non-missing value of the source variable is
+recoded to value 1, the next smallest to 2, and so on.  If the source
+variable has user-missing values, they are recoded to
+consecutive values just above the non-missing values.  For example, if
+a source variables has seven distinct non-missing values, then the
+smallest missing value would be recoded to 8, the next smallest to 9,
+and so on.
+
+Use @subcmd{DESCENDING} to reverse the sort order for non-missing
+values, so that the largest non-missing value is recoded to 1, the
+second-largest to 2, and so on.  Even with @subcmd{DESCENDING},
+user-missing values are still recoded in ascending order just above
+the non-missing values.
+
+The system-missing value is always recoded into the system-missing
+variable in target variables.
+
+If a source value has a value label, then that value label is retained
+for the new value in the target variable.  Otherwise, the source value
+itself becomes each new value's label.
 
 @subcmd{PRINT} is currently ignored.
 
 The @subcmd{GROUP} subcommand is relevant only if more than one variable is to be
 recoded.   It causes a single mapping between source and target values to
-be used, instead of one map per variable.
+be used, instead of one map per variable.  With @subcmd{GROUP},
+user-missing values are taken from the first source variable that has
+any user-missing values.
 
 If @subcmd{/BLANK=MISSING} is given, then string variables which contain only 
 whitespace are recoded as SYSMIS.  If @subcmd{/BLANK=VALID} is given then they
@@ -304,7 +333,8 @@ When @cmd{COMPUTE} is specified following @cmd{TEMPORARY}
 @vindex COUNT
 
 @display
-COUNT @var{var_name} = @var{var}@dots{} (@var{value}@dots{}).
+COUNT @var{var_name} = @var{var}@dots{} (@var{value}@dots{})
+    [/@var{var_name} = @var{var}@dots{} (@var{value}@dots{})]@dots{}
 
 Each @var{value} takes one of the following forms:
         @var{number}