Normalize y-values from lists

Question

I have have some (x,y) lists generated by:

Do[Spec[2*i] = AllData[[All, (2*i + 1) ;; (2*i + 2)]], {i, 0, 10}];

So that Spec[0], Spec[2] ... Spec[20] are (x,y) values from a larger table. I want to normalize the y values for each Spec[i] so that they go from 0 to 1. How can I do that?

Answer 1

mylist = Table[{RandomReal[], RandomReal[{5, 6}]}, 10];

mynewlist = {#[[1]], (#[[2]] - Min[mylist[[All, 2]]])/(Max[mylist[[All, 2]]] - 
       Min[mylist[[All, 2]]])} & /@ mylist

or shorter:

Transpose[{(a = Transpose[mylist])[[1]], Rescale[a[[2]]]}]

or if this were code golf:

t = Transpose; t[{(a = t[mylist])[[1]], Rescale[a[[2]]]}]

Answer 2

Well, I don't know if this is exactly what you want: (since you haven't provided me AllData)

Say I generate a number of Spec lists of two variables:

    Spec[j_] = Table[Partition[RandomSample[Range[40], 20], 2], {i, 1, 10}][[j]] // Quiet;

and any element say,

    Spec[1]
    (*{{2, 1}, {24, 14}, {17, 28}, {34, 20}, {29, 5}, {8, 15}, {12,  39}, {21, 6}, {10, 35}, {22, 4}}*)

Now, I want to normalize all y's to 0,1 and Thread them together. So, I get, say, Newspec:

   NewSpec[i_] := Thread[{Spec[i][[All, 1]], Normalize[Spec[i][[All, 2]]]}] // N

Your new list with normalized y values is:

    NewSpec[1]
    (*{{2., 0.0150261}, {24., 0.210366}, {17., 0.420732}, {34.,  0.300523}, {29., 0.0751307}, {8., 0.225392}, {12., 0.586019}, {21.,  0.0901568}, {10., 0.525915}, {22., 0.0601045}}*)