[Tutor] Generate list-of-transforms

[spir]

On 12/05/2013 11:52 AM, Steven D'Aprano wrote:
> There is a name for this: it is called a RANK TABLE. In the example
> given:
>
> values = [3, 1, 2, 5, 4]
>
> the rank table gives the rank of each element, that is, the position
> they would get after sorting. In this case, the rank table is not
> terribly exciting, because the items are equal to their ranks, less 1
> because Python counts indexes from 0 rather than 1:

Yes, that's it; and there are two kinds of such rank tables, in principle, 
depending on what is the key of the table:
* either the index the the original (unsorted) list
* or the value (if it can be a dict key)

["foo", "bar", "baz"] -->
* {0:2, 1:0, 2:1}
* {"foo":2, "bar":0, "baz":1}
(This is hard to get right with 0-based indexes! We don't think that way -- at 
least _I_ don't.)

But, as already implicitely shown by Steven, in case keys are the original 
indexes, one can as well make it a plain list:
* [2, 0, 1]

Denis