Re: Part ([[...]]) and span (;;)
- To: mathgroup at smc.vnet.net
- Subject: [mg84623] Re: Part ([[...]]) and span (;;)
- From: Norbert Marxer <marxer at mec.li>
- Date: Mon, 7 Jan 2008 02:40:45 -0500 (EST)
- References: <flqcg3$k5e$1@smc.vnet.net>
On 6 Jan., 12:02, nigol <dario.butt... at gmail.com> wrote:
> In the Mathematica 6 help is written:
> =A0 =A0Common spans of parts include:
> =A0 =A0expr[[;;,j]] =A0 =A0 =A0 =A0 =A0 column j
> =A0 =A0If any of the Subscript[list, i] are All or ;;, all parts at that
> level are kept.
>
> On my platform the following works:
> In[1]:= {{a, b, c}, {d, e, f}, {g, h, i}}[[All, 2]]
> Out[1]= {b, e, h}
>
> but the following does not work:
> {{a, b, c}, {d, e, f}, {g, h, i}}[[;; , 2]]
> Syntax::sntxf: ";;" cannot be followed by ",2".
> Syntax::tsntxi: ",2" is incomplete; more input is needed.
> Syntax::sntxi: Incomplete expression; more input is needed.
>
> In[2]:= $Version
> Out[2]= "6.0 for Microsoft Windows (32-bit) (June 19, 2007)"
>
> Is this problem common to other platforms?
> Thanks,
> Dario
Hello
The documentation (at "More Information" for "Part") is not correct.
As cou can see under "Basic Examples" a few lines further down you
have to use (;;) instead of just ;;
i.e. {{a, b, c}, {d, e, f}, {g, h, i}}[[(;;), 2]]
works as expected.
Best Regards
Norbert Marxer