Re: rewritten N OF CASES documentation

[John Darrington]

Looks good to me.

On Mon, Jul 09, 2007 at 10:10:39PM -0700, Ben Pfaff wrote:
     The N OF CASES documentation is quite wrong, and poorly written
     besides.  I wrote it; it's my fault.  Here's an update.
     Comments?
     
     *** data-selection.texi    05 Jun 2007 22:14:42 -0700      1.6
     --- data-selection.texi    09 Jul 2007 22:07:52 -0700      
     ***************
     *** 51,101 ****
       N [OF CASES] num_of_cases [ESTIMATED].
       @end display
       
     ! Sometimes you may want to disregard cases of your input.  @cmd{N} can
     ! do this.  @code{N 100} tells PSPP to disregard all cases after the
     ! first 100.
     ! 
     ! If the value specified for @cmd{N} is greater than the number of cases
     ! read in, the value is ignored.
     ! 
     ! @cmd{N} does not discard cases or prevent them from being read.  It
     ! just causes cases beyond the last one specified to be ignored by data
     ! analysis commands.
     ! 
     ! A later @cmd{N} command can increase or decrease the number of cases
     ! selected.  (To select all the cases without knowing how many there are,
     ! specify a very high number: 100000 or whatever you think is large 
enough.)
     ! 
     ! Transformation procedures performed after @cmd{N} is executed
     ! @emph{do} cause cases to be discarded.
     ! 
     ! @cmd{SAMPLE} and @cmd{SELECT IF} have
     ! precedence over @cmd{N}---the same results are obtained by both of the
     ! following fragments, given the same random number seeds:
     ! 
     ! @example
     ! @address@hidden up, read in address@hidden
     ! N 100.
     ! SAMPLE .5.
     ! @address@hidden address@hidden
     ! 
     ! @address@hidden up, read in address@hidden  
     ! SAMPLE .5.
     ! N 100.
     ! @address@hidden address@hidden
     ! @end example
     ! 
     ! Both fragments above first randomly sample approximately half of the
     ! cases, then select the first 100 of those sampled.
     ! 
     ! @cmd{N} with the @code{ESTIMATED} keyword gives an
     ! estimated number of cases before @cmd{DATA LIST} or another command to
     ! read in data.  @code{ESTIMATED} never limits the number 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 SAMPLE
       @section SAMPLE
     --- 51,81 ----
       N [OF CASES] num_of_cases [ESTIMATED].
       @end display
       
     ! @cmd{N OF CASES} limits the number of cases processed by any
     ! procedures that follow it in the command stream.  @code{N OF CASES
     ! 100}, for example, tells PSPP to disregard all cases after the first
     ! 100.
     ! 
     ! When @cmd{N OF CASES} is specified after @cmd{TEMPORARY}, it affects
     ! only the next procedure (@pxref{TEMPORARY}).  Otherwise, cases beyond
     ! the limit specified are not processed by any later procedure.
     ! 
     ! If the limit specified on @cmd{N OF CASES} is greater than the number
     ! of cases in the active file, it has no effect.
     ! 
     ! When @cmd{N OF CASES} is used along with @cmd{SAMPLE} or @cmd{SELECT
     ! IF}, the case limit is applied to the cases obtained after sampling or
     ! case selection, regardless of how @cmd{N OF CASES} is placed relative
     ! to @cmd{SAMPLE} or @cmd{SELECT IF} in the command file.  Thus, the
     ! commands @code{N OF CASES 100} and @code{SAMPLE .5} will both randomly
     ! sample approximately half of the active file's cases, then select the
     ! first 100 of those sampled, regardless of their order in the command
     ! file.
     ! 
     ! @cmd{N OF CASES} with the @code{ESTIMATED} keyword gives an estimated
     ! number of cases before @cmd{DATA LIST} or another command to read in
     ! data.  @code{ESTIMATED} never limits the number of cases processed by
     ! procedures.  PSPP currently does not make use of case count estimates.
       
       @node SAMPLE
       @section SAMPLE
     
     -- 
     Ben Pfaff 
     http://benpfaff.org
     
     
     _______________________________________________
     pspp-dev mailing list
     address@hidden
     http://lists.gnu.org/mailman/listinfo/pspp-dev

-- 
PGP Public key ID: 1024D/2DE827B3 
fingerprint = 8797 A26D 0854 2EAB 0285  A290 8A67 719C 2DE8 27B3
See http://pgp.mit.edu or any PGP keyserver for public key.

signature.asc
Description: Digital signature