Add noise (random values) to data

Question

I have a data set(x,y,z) corresponding to a hemisphere, to which I want to add some controlled noise (random values) to make the x,y,z values diverge.

data = Flatten[ Table[{i, j, i^2 + j^2}, {i, -10, 10, 1}, {j, -10, 10, 1}], 1]

The above is a 3 coordinate set (x,y,z) values for a hemisphere. How do I add random noise to it?

Thank you

Flatten[ Table[{i, j, i^2 + j^2 + RandomReal[{-10, 10}]}, {i, -10, 10, 1}, {j, -10, 10, 1}], 1];? — Dr. belisarius, Jan 21 '13 at 04:18
Ahh sorry.. the above code gives me 3 points = (x,y,z) and I want to add noise to x,y,z, that is some random values (range 0 - 5) to x,y,z — Mun, Jan 21 '13 at 04:26
@belisarius, I just realised you made some changes to the code you quoted above. This works fine too. Thanks! — Mun, Jan 21 '13 at 04:44
Be careful because @kguler's and mine aren't equivalent. He is "noising" the three coordinates, while I was adding noise just to z — Dr. belisarius, Jan 21 '13 at 04:47

score 8 · Accepted Answer · answered Jan 21 '13 at 04:38

8

 data = Flatten[Table[{i, j, i^2 + j^2}, {i, -10, 10, 1}, {j, -10, 10, 1}], 1];
 noisydata = # + RandomReal[5, 3] & /@ data;
 Row[{ListPlot3D[data, ImageSize -> 300, BoxRatios -> 1],
   ListPlot3D[noisydata, ImageSize -> 300, BoxRatios -> 1]}]

enter image description here

answered Jan 21 '13 at 04:38

kglr

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Add noise (random values) to data

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