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?