What is the simplest way to make the sum of the positive elements in a Nx1 matrix equal 1? I end up converting the matrix to an array, doing the normalization, then converting the array back to a matrix.

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m = M.randn(10,1) m[m > 0,:] = m[m > 0,:] / m[m > 0,:].sum()

exceptions.ValueError Traceback (most recent call last) <ipython console> ValueError: array is not broadcastable to correct shape

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a = M.asarray(m) a[a > 0,:] = a[a > 0,:] / a[a > 0,:].sum() a[a > 0,:].sum()

1.0

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m = M.asmatrix(a)