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help for creplace                                                (Roger Newson)
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Exchange values cyclically between variables

        creplace [ varlist ] [if] [in] [ , previous ]


Description

    creplace is an extended version of replace, which exchanges values
    cyclically between variables in a list of two or more variables.  By
    default, the values in each variable are replaced by values from the next
    variable in the list, or by values from the first variable, in the case
    of the last variable.  Optionally, the values in each variable are
    replaced by values from the previous variable in the list, or by values
    from the last variable, in the case of the first variable.  If there are
    only two variables in the list, then their values will simply be
    exchanged.  Variables in the list must be all numeric or all string.
    After exchanging the values, creplace will compress these variables to
    the smallest storage type possible without loss of information.


Options for creplace

    previous specifies that the values of each variable in the list will be
        replaced by values from the previous variable in the list, or by
        values from the last variable in the list, in the case of the first
        variable in the list.  If previous is not specified, then the values
        of each variable in the list will be replaced by values from the next
        variable in the list, or by values from the first variable in the
        list, in the case of the last variable in the list.


Remarks

    creplace can cyclically exchange values between a list with any number of
    variables greater than one.  However, in most cases, there will only be
    two variables, and their values will be exchanged pairwise, at least in
    the subset of observations specified by the if and in qualifiers.

    creplace is commonly used in output datasets (or resultssets) produced by
    the parmest package, downloadable from SSC.  Such output datasets have
    one observation for each of a set of estimated parameters, and data on
    estimates and lower and upper confidence limits, which are stored in
    three variables.  The user may replace the values of these variables to
    perform an end point transformation on the confidence intervals.  If the
    end point transformation is decreasing, then the user may use creplace to
    exchange values of the lower and upper confidence limits, after the
    transformation has been performed.


Examples

        .creplace weight length headroom

        .creplace weight length headroom, previous

        .creplace min95 max95

        .creplace min95 max95 if parm=="length"


Author

    Roger Newson, National Heart and Lung Institute, Imperial College London,
    UK.
    Email: r.newson@imperial.ac.uk


Also see

    Manual:  [D] generate

      Help:  [D] replace, [D] generate
             parmest if installed