tsrevar.hlp

是一个经济学管理应用软件 很难找的 但是经济学学生又必须用到

{smcl}
{* 14feb2005}{...}
{cmd:help tsrevar}
{hline}

{title:Title}

{p2colset 5 21 23 2}{...}
{p2col :{hi:[TS] tsrevar} {hline 2}}Time-series operator programming 
command{p_end}
{p2colreset}{...}


{title:Syntax}

{p 8 17 2}
{cmd:tsrevar} [{varlist}] {ifin} [{cmd:,} {opt sub:stitute} {opt l:ist}]

{phang}
You must {helpb tsset} your data before using {cmd:tsrevar}.


{title:Description}

{pstd}
{cmd:tsrevar, substitute} takes a {varlist} that might contain
{it:op.varname} combinations and substitutes equivalent temporary variables
for the combinations.

{pstd}
{cmd:tsrevar, list} creates no new variables.  It returns in {hi:r(varlist)}
the list of base variables corresponding to {it:varlist}.


{title:Options}

{phang}
{cmd:substitute} specifies that {cmd:tsrevar} resolve {it:op.varname}
combinations by creating temporary variables as described above.
{cmd:substitute} is the default action taken by {cmd:tsrevar}; you do not need
to specify the option.

{phang}
{cmd:list} specifies that {cmd:tsrevar} return a list of
base variable names.


{title:Example: {cmd:tsrevar, substitute}}

{pstd}Given the command

{phang2}{cmd:. tsrevar sp l.gnp d.gnp r lnr}

{pstd}
{cmd:tsrevar} would create two temporary variables, one for {cmd:l.gnp} and
another for {cmd:d.gnp}.  Returned in {hi:r(varlist)} would be

{p 8 11 2}
{cmd:sp} <{it:first_temporary_variable}> <{it:second_temporary_variable}> 
  {cmd:r lnr}

{pstd}
Thus, {cmd:sp} corresponds to {cmd:sp}, <{it:first_temporary_variable}> to
{cmd:l.gnp}, and so on.

{pstd}
Note that {cmd:tsrevar} does not create unnecessary temporary variables:

{p 8 12 2}
{cmd:. tsrevar sp l.gnp d.gnp r lnr l.gnp}

{p 8 12 2}
{cmd:. display "'r(varlist)'"}{p_end}
{p 8 12 2}
sp __000000 __000001 r lnr __000000

{p 8 12 2}
{cmd:. tsrevar r l.gnp l2.gnp}

{p 8 12 2}
{cmd:. display "'r(varlist)'"}{p_end}
{p 8 12 2}
r __000000 __000002

{pstd}
Note that in the first {cmd:tsrevar} command, {cmd:l.gnp} appeared twice
and the same temporary variable was used to refer to both.  Note that in the
second {cmd:tsrevar} command, {cmd:l.gnp} appeared again and the originally
created temporary variable was again used.

{pstd}
Remember that temporary variables automatically vanish when the program
concludes.


{title:Example: {cmd:tsrevar, list}}

{pstd}
Given the command

{phang2}{cmd:. tsrevar sp l.gnp d.gnp r lnr, list}

{pstd}
no variables would be created; the returned {hi:r(varlist)} would contain

{phang2}{hi:sp gnp r lnr}

{pstd}
which are the base variables on which the above list depends.  The ordering
of the list will probably be different than shown; base variables will be
listed in the order in which they appear in the dataset.


{title:Also see}

{psee}
Manual:  {bf:[TS] tsrevar}{p_end}

{psee}
Online:  {helpb syntax}, {helpb unab}{p_end}