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Re: opposite of AppendTo

  • To: mathgroup at smc.vnet.net
  • Subject: [mg124359] Re: opposite of AppendTo
  • From: Bob Hanlon <hanlonr357 at gmail.com>
  • Date: Tue, 17 Jan 2012 03:33:33 -0500 (EST)
  • Delivered-to: l-mathgroup@mail-archive0.wolfram.com

s = Array[x, 4];

AppendTo[s, e]

{x[1], x[2], x[3], x[4], e}

s = Most[s]

{x[1], x[2], x[3], x[4]}

AppendTo[s, e]

{x[1], x[2], x[3], x[4], e}

s = Drop[s, -1]

{x[1], x[2], x[3], x[4]}

AppendTo[s, e]

{x[1], x[2], x[3], x[4], e}

s = s /. e -> Sequence[]

{x[1], x[2], x[3], x[4]}


Bob Hanlon

On Mon, Jan 16, 2012 at 5:12 PM, burke <burket at mailbox.sc.edu> wrote:
> AppendTo[s,e] appends "e" to "s" and then RESETS "s". How does one
> delete or remove an element "e" from a list "s" and then RESET "s"?
> The _reset_ is my problem.  I want to be able to add and delete
> elements of a list (a list of graphical elements with very low
> opacity).  I can "appendto" the list at will but am unable to delete
> elements (using Delete, DeleteCases, Except, Select, etc.). Deleting
> "e" from "s" is easy enough, but resetting "s" seems impossible.
> Help!!
>



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