Re: List Replace Problems
- To: mathgroup at smc.vnet.net
- Subject: [mg59862] Re: [mg59831] List Replace Problems
- From: Pratik Desai <pdesai1 at umbc.edu>
- Date: Wed, 24 Aug 2005 06:30:45 -0400 (EDT)
- References: <200508230851.EAA03004@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
wesh wrote:
>I want to perform some element by element operations on a class of
>lists. For a given list The operation in a much simplified form can be
>characterized by
>
>a = {1, 3, 5, 7, 9};
>Do[a[[i]] /= i, {i, 1, 5}];
>a
>
>Out[38]=
>{1, 3/2, 5/3, 7/4, 9/5}
>
>Now, however, if I try to define a function to do this for a general
>list, namely,
>
>dlst[u_List] =
> Do[u[[i]] /= i, {i, 1, 5}];
>a = {1, 3, 5, 7, 9};
>dlst[a];
>a
>
>Set::setps:
>({1, 2, 3, 4, 5}) in assignment of part is not a symbol. ! More ...
>
>Out[39]=
>{1, 3, 5, 7, 9}
>
>I get the above error. It says I'm trying to assign one number to
>another number. Why does Mathematica perform in the first case but
>refuse to in the second.
>
>I tried
>
>b = Do[ReplacePart[a, a[[i]]/i, i], {i, 1, 5}]
>
>but it doesn't even bother to return an error message.
>
>
>How, can I get the desired function?
>
>Thanks,
>
>Wesh
>
>
>
How about some thing like this using module
dlst[u_?ListQ, r_?IntegerQ] := Module[{list1, list2}, list1 =
u; If[r > Length[list1], Print["Incompatible Iterator please revise
your argument"], list2 = Table[list1[[s]]/s, {s, 1, r, 1}]]]
Hope this helps
Pratik
--
Pratik Desai
Graduate Student
UMBC
Department of Mechanical Engineering
Phone: 410 455 8134
- References:
- List Replace Problems
- From: wesh <wesh@acm.org>
- List Replace Problems