Re: Table of tables
- To: mathgroup at smc.vnet.net
- Subject: [mg113285] Re: Table of tables
- From: Bob Hanlon <hanlonr at cox.net>
- Date: Fri, 22 Oct 2010 01:35:05 -0400 (EDT)
t = {{{-1, -1, -2}, {-1, -1, -3}}, {{-1, -1, -4}, {-1, -1, -5}}};
t /. {x_, y_, z_?NumericQ} :> {x, y, Abs[z]}
{{{-1, -1, 2}, {-1, -1, 3}}, {{-1, -1, 4}, {-1, -1, 5}}}
or
Map[MapAt[Abs, #, -1] &, t, {2}]
{{{-1, -1, 2}, {-1, -1, 3}}, {{-1, -1, 4}, {-1, -1, 5}}}
% == %%
True
Bob Hanlon
---- Luiz Melo <luiz.melo at polymtl.ca> wrote:
=============
Thanks Sebastian and Valeri for the help.
I'm actually looking for a function that operates only on the third row of each
column-matrix terms(which happen to be complex in the example I gave), but
leaves the other terms intact. Consider a different example:
Let
t = {{{-1, -1, -2}, {-1, -1, -3}}, {{-1, -1, -4}, {-1, -1, -5}}};
how can I get
{{{-1, -1, 2}, {-1, -1, 3}}, {{-1, -1, 4}, {-1, -1, 5}}};
that is, in this case, I need a function that takes the Abs[] of the 3rd row of
each sub-matrix and leaves the other terms intact.
Regards,
Luiz
> Hi Luiz!
>
> Luiz Melo wrote:
> > Given
> >
> > t = {{{-1, -1, -2+2I}, {-1, -1, 3-I}}, {{-1, -1, 4+I}, {-1, -1, -5-5I}}};
> >
> > how can I extract the imaginary part of the complex elements to obtain
> >
> > {{{-1, -1, 2}, {-1, -1, -1}}, {{-1, -1, 1}, {-1, -1, -5}}};
>
> What about:
>
> Function[{e}, If[Im[e] == 0, e, Im[e]], Listable][t]
>
> There seems to be no ComplexQ therefore I test with "Im[e] == 0" if it
> is not a complex number.
>
> Cheers,
>
> Sebastian
>