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In the help resource for the multivariate normal sampling function in SciPy, they give the following example:
x,y = np.random.multivariate_normal(mean,cov,5000).T My question is rather basic: what does the final .T actually do?
Thanks a lot, I know it is fairly simple, but it is hard to look in Google for ".T".
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In Python strings, the backslash "\" is a special character, also called the "escape" character. It is used in representing certain whitespace characters: "\t" is a tab, "\n" is a newline, and "\r" is a carriage return. Conversely, prefixing a special character with "\" turns it into an ordinary character.
T is just a convenient notation, and that . transpose(*axes) is the more general function and is intended to give more flexibility, as axes can be specified.
X.T means transpose of X.
property property matrix. T. Returns the transpose of the matrix.
The .T accesses the attribute T of the object, which happens to be a NumPy array. The T attribute is the transpose of the array, see the documentation.
Apparently you are creating random coordinates in the plane. The output of multivariate_normal() might look like this:
>>> np.random.multivariate_normal([0, 0], [[1, 0], [0, 1]], 5) array([[ 0.59589335, 0.97741328], [-0.58597307, 0.56733234], [-0.69164572, 0.17840394], [-0.24992978, -2.57494471], [ 0.38896689, 0.82221377]]) The transpose of this matrix is:
array([[ 0.59589335, -0.58597307, -0.69164572, -0.24992978, 0.38896689], [ 0.97741328, 0.56733234, 0.17840394, -2.57494471, 0.82221377]]) which can be conveniently separated in x and y parts by sequence unpacking.
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