Select elements from 2D list with stride "t"

Question

I would like to select elements from 2D list according to variable position (i.e. stride). For example:

x=Range@25 ~Partition~ 5

I want a command to select elements with stride t=2 as y={{1,3,5},{11,13,15},{21,23,25}}. Simply, take one and leave one. What if t=3,4,...etc?

Thanks

kglr · Accepted Answer · 2018-10-12 08:04:12Z

2

t = 2;
Partition[Range[25], 5][[;; ;; t, ;; ;; t]]

{{1, 3, 5}, {11, 13, 15}, {21, 23, 25}}

Or, as suggested by J.M.issomewhatokey, use Take:

Take[Partition[Range[25], 5], {1, -1, t}, {1, -1, t}]

{{1, 3, 5}, {11, 13, 15}, {21, 23, 25}}

Partition[Range[25], 5][[;; ;; 3, ;; ;; 3]]

{{1, 4}, {16, 19}}

answered Oct 12, 2018 at 8:00

kglr

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$\begingroup$ Take[] ought to work here, too. $\endgroup$
– J. M.'s slightly less busy ♦
Oct 12, 2018 at 8:03
$\begingroup$ @J.M. yes it does. Thank, you. $\endgroup$
– kglr
Oct 12, 2018 at 8:05
$\begingroup$ Thanks :) it works well... $\endgroup$
– Alien Tsukuba
Oct 12, 2018 at 8:11
$\begingroup$ @AlienTsukuba, you are most welcome. $\endgroup$
– kglr
Oct 12, 2018 at 8:12

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