Normalize to unit norm
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I have a variable containing a probability distribution (just an one-dimensional array of values). How can I normalize a to unit norm?
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Wayne King
2012-5-27
If you want to normalize a vector to have unit L2 norm.
x = randn(100,1);
x = x./norm(x,2);
norm(x,2)
12 个评论
Nuchto
2012-5-27
Oleg Komarov
2012-5-27
They're in ans.
Nuchto
2012-5-27
Oleg Komarov
2012-5-27
My mistake, ans proves that the x values are normalized to a unit L2 norm.
Nuchto
2012-5-27
Nuchto
2012-5-30
Oleg Komarov
2012-5-30
x./sum(x)
Now, this is not a unit norm normalization (as I understand it, thus nobody answered earlier).
Nuchto
2012-6-1
Kye Taylor
2012-6-1
"Unit norm" itself is not well-defined without specifying the norm itself.
@Nuchto, it sounds like you are looking for the l1 norm, while the initial answer provided by @Wayne is using the l2 norm...
As @Oleg suggested, you can normalize by the sum to obtain the same as the following
normX = x/norm(x,1)
Be careful if simply normalizing by the sum because it doesn't account for negative values in the original vector. However, since you are working with a probability distribution, that isn't an issue.
Oleg Komarov
2012-6-1
"same as the following
normX = x/norm(x,1)"
IF all x >0.
Nuchto
2012-6-2
Oleg Komarov
2012-6-2
http://en.wikipedia.org/wiki/Norm_%28mathematics%29, Euclidean vs taxicab
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