Re: Flatten and BlockProcessing

• To: mathgroup at smc.vnet.net
• Subject: [mg65654] Re: Flatten and BlockProcessing
• From: Jean-Marc Gulliet <jeanmarc.gulliet at gmail.com>
• Date: Wed, 12 Apr 2006 06:00:03 -0400 (EDT)
• Organization: The Open University, Milton Keynes, UK
• References: <e1fp4f\$beo\$1@smc.vnet.net>
• Sender: owner-wri-mathgroup at wolfram.com

```Maarten van der Burgt wrote:
> Hallo,
>
> I have a structure M:
>
> M = {{{{a, b}, {e, f}}, {{c, d}, {g, h}}}, {{{k, l}, {o, p}}, {{m, n}, {q,
> r}}}}
>
>
> M//Dimensions
>
> gives
>
> {2, 2, 2, 2},
>
> (or more general {n1, n2, m1, m2}; M is the result of the BlockProcessing
> function from the Image Processing package)
>
> Does anyone know an elegant way of 'flattening' M to give
>
> {{a, b, c, d}, {e, f, g, h}, {k, l, m, n}, {o, p, q, r}}
>
> with dimensions {4, 4} (or more general {n1*m1, n2*m2})?
>
>
> Thanks for your help,
>
>
> Maarten
>
Hi Marteen,

Something along the following lines might help:

In[1]:=
M = {{{{a, b}, {e, f}}, {{c, d}, {g, h}}},
{{{k, l}, {o, p}}, {{m, n}, {q, r}}}};

In[2]:=
Partition[Flatten[Partition[Flatten[M], 2, 4]], 4]

Out[2]=
{{a, b, c, d}, {k, l, m, n}}

In[3]:=
Partition[Flatten[Partition[Drop[Flatten[M], 2], 2,
4]], 4]

Out[3]=
{{e, f, g, h}, {o, p, q, r}}

In[4]:=
Union[%%, %]

Out[4]=
{{a, b, c, d}, {e, f, g, h}, {k, l, m, n},
{o, p, q, r}}

Regards,
Jean-Marc

```

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