Re: Adding value to some elements of a list
- To: mathgroup at smc.vnet.net
- Subject: [mg131042] Re: Adding value to some elements of a list
- From: Ray Koopman <koopman at sfu.ca>
- Date: Wed, 5 Jun 2013 04:38:18 -0400 (EDT)
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- Delivered-to: l-mathgroup@wolfram.com
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a = {10,20,30,40,50,60};
b = {2,4,6};
c = 17;
MapAt[#+c&, a, List/@b]
{10,37,30,57,50,77}
----- Joerg Lenhardt <joerg.lenhardt at FernUni-Hagen.de> wrote:
> Hello,
>
> I have two lists. One containing values, another containing indexes to
> the first list. I want to add a value to all elements of the first list
> when its index is in the second list:
>
> a={10,20,30,40,50,60}
>
> b={2,4,6}
>
> c=17
>
> ==>
>
> {10,20+17,30,40+17,50,60+17}
>
> I would be glad if anyone have a simple solution for that problem - I am
> convinced there is one ...
>
> Best regards
> J. Lenhardt