about tuples

[Fred Lee]

how to use the option conditionals to realize that var1 var2 var3 appear together or disappear together?

[Nick Cox]

tuples (Joseph Luchman and friends) is from SSC, as you are asked to explain (FAQ Advice #12).

You don't need that option. With your rules either

var1 var2 var3

appears as one inseparable trio or it does not. The help explains:

As usual, double quotes may be used to bind. Thus "a b c" d e is a list of three items, not five.

Here is a demonstration:

. tuples "var1 var2 var3" var4 var5

. mac li
<stuff irrelevant to the question>
_ntuples:       7
_tuple7:        var1 var2 var3 var4 var5
_tuple6:        var1 var2 var3 var4
_tuple5:        var1 var2 var3 var5
_tuple4:        var4 var5
_tuple3:        var1 var2 var3
_tuple2:        var4
_tuple1:        var5

By the way, check out nestreg -- which may be what you seek.

[Fred Lee]

Thanks a lot for your tips!