m={{a, b, c, p}, {d, e, f, x}, {g, h, k, z}, {u, v, w, y}};
I want to swap 1st and 2nd rows by 4th and 3rd rows respectively. And then, swap 1st and 2nd columns by 4th and 3rd columns.
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1 Answer
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OK, encouraged by belisarius, here's the way.
If you know that Reverse exists you may use:
Reverse /@ Reverse @ m
then you could check the docs and realise that Reverse has 2nd argument:
Reverse[m, {1, 2}]
But if you don't but you are amazed by Span+Part you can end up with:
m[[;; , {4, 3, 2, 1}]][[{4, 3, 2, 1}]]
or even more Span: :)
m[[;; , -1 ;; 1 ;; -1]][[-1 ;; 1 ;; -1]]
Why is multidimensional Reverse slow? - nice question where I've learned about -1;;1;;-1
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1$\begingroup$ Congratulations on joining the 20K club! :-) For some reason I still think of you as a "new" member but you have become a pillar of the community, and not by "reputation" alone. $\endgroup$ Apr 29, 2014 at 23:35
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$\begingroup$ @Mr.Wizard Thank you for those kind words :) I do enjoy being here :), almost each day I can learn, or at least face, something new so thank you community of Mathematica.SE :) $\endgroup$– Kuba ♦Apr 30, 2014 at 5:12
Reverse[m, {1, 2}]. Related: (2546) and (19726) $\endgroup$Reversehas second argument, but if you need to reverse something it is easy to face it in docs :) So my point is that it should be closed, but let's see what community says :) $\endgroup$