Re: normalize a table

• To: mathgroup at smc.vnet.net
• Subject: [mg72790] Re: [mg72768] normalize a table
• From: Bob Hanlon <hanlonr at cox.net>
• Date: Sat, 20 Jan 2007 02:36:29 -0500 (EST)

```data={{1,0.2},{2,0.3},{3,0.4},{4,0.5}};

#/{Max[data[[All,1]]],1}&/@data

{{1/4, 0.2}, {1/2, 0.3}, {3/4, 0.4}, {1, 0.5}}

A different normalization (first terms sum to unity):

#/{Total[data[[All,1]]],1}&/@data

{{1/10, 0.2}, {1/5, 0.3}, {3/10, 0.4}, {2/5, 0.5}}

Bob Hanlon

---- Ruth <ruth.lazkoz at ehu.es> wrote:
> Hi,
>
> I want to do something really simple, which is take a table made of
> pairs and normalize the first number in each pair by dividing by the
> largest.
>
> For instance, I want to transform this list
>
> {{1,0.2},{2,0.3},{3,0.4},{4,0.5}}
>
> into this one
>
> {{1/4, 0.2}, {1/2, 0.3}, {3/4, 0.4}, {1, 0.5}}
>
> The way i did it is through the chain of commands
>
> firsttable={{1,0.2},{2,0.3},{3,0.4},{4,0.5}};
>
>
> top=Max[Table[firsttable[[i,1]],{i,1,Length[firsttable]}]];
>
>
> mytable=Do[newtable=ReplacePart[newtable,newtable[[i,1]]/top,{i,
> 1}],{i,1,Length[firsttable]}]
>
> There must be a more elegant way to do it, but @&# and commands like
> those are still hard to handle for me, and I could not work it out
>