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Re: Set in Scan


Johannes Ludsteck [ludsteck at zew.de] wrote:

> I have to do replacements in very long lists. An efficient way to do 
> this is to use
> 
> x[[index]]=newElement.
> 
> This, however, doesn't work if I want to do replacements for a set of 
> lists. If I try to replace the third element in the lists v1, v2 
> and v3 by 
> typing
> 
> Scan[#[[3]] = newElement &, {v1,v2,v3}]
> I get the error message
> Set::setps: #1 in assignment of part is not a symbol.
> 
> Any suggestions?

I suggest you use ReplacePart instead of direct assignment:

In[1]:=
g[x_]:= ReplacePart[x,newElement,3]

and then Map this function on the list {v1, v2, v3} thus:

In[2]:=
g[#]&/@{v1,v2,v3}

This works fine.

Tomas Garza
Mexico City


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