Re: Specifying arguments inside nested functions
- To: mathgroup at smc.vnet.net
- Subject: [mg46121] Re: [mg46107] Specifying arguments inside nested functions
- From: "Sseziwa Mukasa,,(978) 536-2359" <mukasa at jeol.com>
- Date: Sat, 7 Feb 2004 04:02:02 -0500 (EST)
- References: <200402060915.EAA19269@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
On Feb 6, 2004, at 4:15 AM, Ray Koopman wrote:
> I have two matrices, A and B, that have the same number of columns.
> I want to select the rows of A that differ in every position from
> every row of B. So I write
>
> Select[A, And@@Map[Inner[Unequal,#1,#2,And]&, B]& ]
>
> But that won't work, because I have no way to tell Inner that one of
> its arguments should be the row of A that is being tested by Select,
> and the other argument should be the row of B from Map.
>
> Now, I realize that there are ways around the problem in this
> particular case. For instance, the Select test could be
>
> And@@Map[FreeQ[Rest[#],First[#]]&, Transpose@Prepend[B,#]]&
>
> which checks B a column at a time and might well be more efficient.
> However, this is not the first time I've run into the problem of
> specifying arguments inside nested functions, and I wonder how other
> people handle it. Is there a general solution, or must I always
> ad hoc it?
Use the form of Function that allows named parameters eg.
Select[A, Function[{r},And@@Map[Inner[Unequal,r,#,And]&,B]]]
Regards,
Ssezi
- References:
- Specifying arguments inside nested functions
- From: koopman@sfu.ca (Ray Koopman)
- Specifying arguments inside nested functions