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Re: Drop elements from list

  • To: mathgroup at smc.vnet.net
  • Subject: [mg94200] Re: [mg94161] Drop elements from list
  • From: Bob Hanlon <hanlonr at cox.net>
  • Date: Sat, 6 Dec 2008 19:59:13 -0500 (EST)
  • Reply-to: hanlonr at cox.net

a = Array[x, {20}];

Drop[Drop[a, {7, 10}], {2, 5}]

{x(1),x(6),x(11),x(12),x(13),x(14),x(15),x(16),x(17),x(18),x(19),x(20)}

Fold[Drop[#1, #2] &, a, {{7, 10}, {2, 5}}]

{x(1),x(6),x(11),x(12),x(13),x(14),x(15),x(16),x(17),x(18),x(19),x(20)}

Or slightly more succinctly with Fold

Fold[Drop[##] &, a, {{7, 10}, {2, 5}}]

{x(1),x(6),x(11),x(12),x(13),x(14),x(15),x(16),x(17),x(18),x(19),x(20)}

% == %% == %%%

True


Bob Hanlon

---- SigmundV <sigmundv at gmail.com> wrote: 

=============
Dear group,

Consider a list of length, say, 20:

a = RandomReal[{},20];

How would you then drop/delete elements, say, 2-5 and 7-10 from this
list? The built-in function Drop does not seem to include such a
possibility. I should add that I do not have access to Mathematica 7,
so any solution should work in version 6.

Kind regards,
Sigmund



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