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Re: Creating a new table using values from a column in another table,


Wonko the Sane schrieb:
> Hi all,
> 
> I have a question that I have not been able to work out myself, and so 
> put it to the group to help. I have a set of data points in a table (2 
> columns {{x1,y1},{x2,y2},....,{xn,yn}}) I have performed a fit to the 
> data and have a function f[x] which I would now like to evaluate at each 
> data point (column 1 of the first table) to get a new table 
> {{x1,f[x1]},{x2,f[x2]},....,{xn,f[xn]}}. Is there a way to do this? I 
> hope my request is clear
> 
> Best Regards
> Michael
> 

Coose one (there are most propably more possibilities):

data = Table[ToExpression[StringJoin[#1, ToString[n]]]& /@ {"x", "y"}, {n, 5}]
--> {{x1, y1}, {x2, y2}, {x3, y3}, {x4, y4}, {x5, y5}}

{#1, f[#1]}& /@ First /@ data
--> {{x1, f[x1]}, {x2, f[x2]}, {x3, f[x3]}, {x4, f[x4]}, {x5, f[x5]}}

Transpose[{#1, f /@ #1}&[First[Transpose[data]]]]
--> {{x1, f[x1]}, {x2, f[x2]}, {x3, f[x3]}, {x4, f[x4]}, {x5, f[x5]}}

data /. {x_?AtomQ, _} :> {x, f[x]}
--> {{x1, f[x1]}, {x2, f[x2]}, {x3, f[x3]}, {x4, f[x4]}, {x5, f[x5]}}

Peter


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