On Sun, Jan 04, 2009 at 01:10:16PM -0800, Ben Pfaff wrote:
> Jason Stover <[email protected]> writes:
>
> > I need to combine multiple string values into a single
> > string, in a one-to-one way. For example, in the following
> > data set, there are two variables, each with two values:
> >
> > var1 var2
> > ae f
> > a ef
> >
> > I don't want to just concatenate the values because
> > I would have aef in both cases.
>
> If you strip the whitespace at the end of each string, this is
> true. If you retain the whitespace, then you have "aef " and "a
> ef", which are of course different.
Then what about this:
var1 var2
a e f
a e f
If whitespace is allowed in a value, then we would concatenate to get
"a e f " in both cases.
>
> > I can work around this by using strtol, or something
> > like it.
>
> I don't see how strtol is relevant?
To avoid concatenating, I had been thinking of changing each string to
an integer, then using a one-to-one function from the ordered
n-tuples of integers to the integers. For example, something like:
value ae --> 1
value f --> 2
value aeu --> 87
Then compute n := g (1,2,87), where g is some invertible function. I
had planned to use strtol to map strings to integers. Maybe that's not
the right way.
But to take a step back: What is a good way to create a new union
value from a list of other union values, that avoids collisions?
Concatenate with some character other than whitespace?
-Jason
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