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st: New -keyby- and -addinby- packages on SSC


From   "Newson, Roger B" <r.newson@imperial.ac.uk>
To   <statalist@hsphsun2.harvard.edu>
Subject   st: New -keyby- and -addinby- packages on SSC
Date   Tue, 15 Apr 2008 12:27:52 +0100

Thanks to Kit Baum, a new version of the -keyby- package, and a new
package -addinby-, are now available for download from SSC. In Stata,
use the -ssc- command to do this.

The -keyby- and -addinby- packages are described as below on my website.
The -keyby- package is a "cleaner" version of -sort-, which ensures that
the observations of the memory dataset are uniquely identified, as well
as being sorted, by the sort key variables. And the -addinby- package is
a "cleaner" version of -merge-, which ensures that the observations of
the memory dataset remain identified and/or sorted as before, even after
new data have been added in from a -using- dataset on disk. So,
together, -keyby- and -addinby- can be used to enforce the relational
database model, in which a dataset can be viewed as a mathematical
function, whose domain is the set of available combinations of values of
the primary key variables, and whose range is the set of all possible
combinations of values of the non-key variables.

The -keyby- package has now been updated to Stata Version 10, with some
optimization of internal code. However, users of Stata Version 9 can
still download the old Stata 9 version of -keyby- by typing

net from "http://www.imperial.ac.uk/nhli/r.newson/stata9/";

and selecting the -keyby- package.

Best wishes

Roger


Roger B Newson
Lecturer in Medical Statistics
Respiratory Epidemiology and Public Health Group
National Heart and Lung Institute
Imperial College London
Royal Brompton campus
Room 33, Emmanuel Kaye Building
1B Manresa Road
London SW3 6LR
UNITED KINGDOM
Tel: +44 (0)20 7352 8121 ext 3381
Fax: +44 (0)20 7351 8322
Email: r.newson@imperial.ac.uk 
Web page: www.imperial.ac.uk/nhli/r.newson/
Departmental Web page:
http://www1.imperial.ac.uk/medicine/about/divisions/nhli/respiration/pop
genetics/reph/

Opinions expressed are those of the author, not of the institution.


------------------------------------------------------------------------
----------
package keyby from http://www.imperial.ac.uk/nhli/r.newson/stata10
------------------------------------------------------------------------
----------

TITLE
      keyby: Key the dataset by a variable list

DESCRIPTION/AUTHOR(S)
      keyby sorts the dataset currently in memory by the variables in a
      varlist, checking that the variables in the varlist uniquely
      identify the observations.  This makes the variables in the
varlist
      a primary key for the dataset in memory.  If the user does not
      specify otherwise, then keyby also reorders the variables in the
      varlist to the start of the variable order in the dataset, and
      checks that all values of these variables are nonmissing.  keyby
      can be useful if the user combines multiple datasets using merge,
      which may cause a dataset in memory to become unsorted.
      
      Author: Roger Newson
      Distribution-Date: 13april2008
      Stata-Version: 10

INSTALLATION FILES                                  (click here to
install)
      keyby.ado
      keyby.sthlp
------------------------------------------------------------------------
----------
(click here to return to the previous screen)


------------------------------------------------------------------------
----------
package addinby from http://www.imperial.ac.uk/nhli/r.newson/stata10
------------------------------------------------------------------------
----------

TITLE
      addinby: Add in data from a disk dataset using a foreign key

DESCRIPTION/AUTHOR(S)
      addinby is a "cleaner" alternative version of merge, designed to
      reduce the lines of code in Stata do-files.  It adds variables
and/or
      values to existing observations in the dataset currently in memory
      (the master dataset} from a Stata-format dataset stored in the
file
      filename (the using dataset), using a foreign key of variables
      specified by the keyvarlist to identify observations in the using
      dataset.  The using dataset must be sorted by the variables in the
      keyvarlist, and these variables must identify observations in the
      using dataset uniquely.  Unlike merge, addinby always preserves
the
      master dataset in its original sorting order, and does not add any
      merge-status variables or additional observations.  However,
addinby
      checks that the foreign key uniquely identifies observations in
the
      using dataset, and may optionally check that there are no
unmatched
      observations in the master dataset, and/or check that there are no
      missing values in the foreign key variables in the master dataset.
      
      Author: Roger Newson
      Distribution-Date: 14april2008
      Stata-Version: 10

INSTALLATION FILES                                  (click here to
install)
      addinby.ado
      addinby.sthlp
------------------------------------------------------------------------
----------
(click here to return to the previous screen)

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