Re: Using SQL to group records with similar elements

On 7/21/2011 7:48 PM, John Yeung wrote:

On Thu, Jul 21, 2011 at 7:02 PM, Joe Pluta<joepluta@xxxxxxxxxxxxxxxxx> wrote:

I'm not sure I understand this line:

if values<= master:

You're comparing one list to be less than or equal to another?

Ah, good question. Actually,<= is overloaded with a different
meaning for sets. When both operands are sets, it's equivalent to

if values.issubset(master):

Other "mathy" shorthand notation for sets:>= for .issuperset(), |
for .union(),& for .intersection(), - for .difference(), and ^ for
.symmetric_difference() (XOR).

Thanks. I think I'd prefer .issubset so I don't have to remember which is which, but that's a little bit of the pot calling the kettle black, since in my case I only just recently broke my own habit of using |< and |> (instead of the far more readable *BCAT and *TCAT) in my CL string concatenation. ;)

Joe