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How do I apply the "Take" function to lists?

Posted 9 years ago
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The following code produces three lists. List px contains 20 integers, list bx contains 10 integers and list cx contains 10 integers. I would like to apply the "Take" function to these 3 lists. I am trying to avoid having 100 separate "Take" statements in another worksheet. I keep getting the error below. I would like the output to be in a flatten-able list or a single list. What am I doing wrong!

    (*p=Table[p,{p,1,40,2}]
    Length[p];

    b=Table[b,{b,1,10,1}]
    Length[b];

    c=Table[c,{c,4,13,1}]
    Length[c];*)

    p = {1, 3, 5, 7, 9, 11, 13, 15, 17, 19, 21, 23, 25, 27, 29, 31, 33, 
       35, 37, 39};

    b = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10};

    c = {4, 5, 6, 7, 8, 9, 10, 11, 12, 13};

    Take[p, {b, c}]

    Take::seqs: Sequence specification (+n, -n, {+n}, {-n}, {m, n}, or {m, n, s}) expected at position 2 in Take[{1,3,5,7,9,11,13,15,17,19,21,23,25,27,29,31,33,35,37,39},
{{1,2,3,4,5,6,7,8,9,10},{4,5,6,7,8,9,10,11,12,13}}]. >>
    Take[{1, 3, 5, 7, 9, 11, 13, 15, 17, 19, 21, 23, 25, 27, 29, 31, 33, 
      35, 37, 39}, {{1, 2, 3, 4, 5, 6, 7, 8, 9, 10}, {4, 5, 6, 7, 8, 9, 
       10, 11, 12, 13}}]
POSTED BY: Kent J Jarvis
4 Replies

Sorry,

copied something wrong. One flatten was missing - then the join is not needed anymore either:

Flatten[ Take[p, {#}] & /@ Flatten[{b, c}]]

Cheers, M.

POSTED BY: Marco Thiel
Posted 9 years ago

OK!

Thanks again Marco. It works fine.

Best wishes, Kent

POSTED BY: Kent J Jarvis

Hi,

what about:

Flatten[Take[p, {#}] & /@ Join[{ b, c}]]

Cheers, M.

PS: There seems to be little confusion in your post about p-> px, b-> bx, and c-> cx.

POSTED BY: Marco Thiel
Posted 9 years ago

Thanks Marco,

I am getting the same error. I don't know what is going on. Is there another method I could try? I will edit my first post. I changed the list names to avoid any conflicts (if any).

POSTED BY: Kent J Jarvis
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