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Re: Length and Drop

  • To: mathgroup at smc.vnet.net
  • Subject: [mg32189] Re: Length and Drop
  • From: Jens-Peer Kuska <kuska at informatik.uni-leipzig.de>
  • Date: Sat, 5 Jan 2002 00:10:25 -0500 (EST)
  • Organization: Universitaet Leipzig
  • References: <a13vdg$dgm$1@smc.vnet.net>
  • Sender: owner-wri-mathgroup at wolfram.com

Hi,

Length[Drop[timexp,1]]

is 1

but Drop[] does not change the value of timexp,
it just generate a copy of the value and remove 
one element from the *copy* not from the original.

You need

timexp=Drop[timexp,1]

Regards
  Jens

Steve Gray wrote:
> 
>     The following sequence seems wrong to  me, in that
> after dropping some elements from a list, its Length is
> still the same. I copied this directly from the notebook
> but removed the In[] and Out[] statements.
> 
> timexp={{0,0}} -> {{0,0}}        [this is ok]
> 
> timexp=Append[timexp,{7,8}] -> {{0,0},{7,8}}       [this is ok]
> 
> Length[timexp] -> 2             [this is ok]
> 
> Drop[timexp,1] -> {{7,8}}         [this is ok]
> 
> Length[timexp] -> 2                    [ this is what I did not expect!]
> 
>     Should not Drop reduce the Length of the list by the amount
> dropped?


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