help fvprevar
-------------------------------------------------------------------------------


Version of fvrevar generating permanent result variables


Syntax

        fvprevar [varlist] [if] [in] , generate(stub) [ nolabel substitute
                 tsonly list fast ]

    You must tsset your data before using fvprevar if varlist contains
        time-series operators; see [TS] tsset.


Description

    fvprevar is an extended version of fvrevar, which returns the generated
    result variables as permanent variables (instead of as temporary
    variables), with names prefixed with a user-specified stub.


Options

    generate(stub) must be specified.  It specifies a prefix, used to produce
        names for the generated variables, and suffixed by positive whole
        numbers from 1 to the number of generated variables.

    nolabel specifies that no variable labels will be defined for the
        generated permanent result variables.  If nolabel is not specified,
        then the generated permanent result variables will have variable
        labels equal to the variable characteristic varname[fvrevar], saved
        by fvprevar and fvrevar, containing the expanded name of the virtual
        factor variable corresponding to the generated variable.

    substitute specifies that equivalent, permanent variables, with names
        prefixed using the generate() option, will be substituted for any
        expanded factor variables, interactions, or time-series-operated
        variables in the varlist.  substitute is the default action taken by
        fvprevar; you do not need to specify the option.

    tsonly specifies that results variables will be substituted for only the
        time-series-operated variables in varlist.

    list specifies that all factor-variable operators and time-series
        operators be removed from varlist.  No new variables are created with
        this option.

    fast is an option for programmers.  It specifies that fvprevar will do no
        extra work to restore the original dataset (without the generated
        result variables) if the user presses Break.


Examples

    Setup
        . sysuse auto, clear

    Describe the data
        . describe

    Create five variables b_1, b_2, b_3, b_4 and b_5, containing the values
    for each level of factor variable rep78

        . fvprevar i.rep78, generate(b_)
        . describe b_*


Saved results

    fvprevar saves the following in r():

    Scalars   
      r(ngenvar)     Number of generated result variables

    Macros    
      r(varlist)     the expanded variable list or list of base-variable
                       names

    fvprevar (like fvrevar) also sets, for each generated variable, the
    variable characteristic varname[fvrevar], containing the expanded virtual
    factor variable name for that generated variable.


Also see

    Manual:  [R] fvrevar

      Help:  [R] fvrevar, [TS] tsrevar, [P] syntax, [P] unab