CODEWITHSUNDEEP
pythonspectral-python
russj
russj

Reputation: 25

Function of a backslash in a line of code, not escaping character from string

I am teaching myself all kinds of things at once, which is probably problematic, but I am doing it by simultaneously trying to understand the source code in a library whilst using the same library. In the Spectral Python library there is this function:

def unmix(data, members):
    '''
    Perform linear unmixing on image data.

    USAGE: mix = unmix(data, members)

    ARGUMENTS:
        data                The MxNxB image data to be unmixed
        members             An CxB array of C endmembers
    RETURN VALUE:
        mix                 An MxNxC array of endmember fractions.

    unmix performs linear unmixing on the image data.  After calling the
    function, mix[:,:,i] will then represent the fractional abundances
    for the i'th endmember. If the result of unmix is returned into 'mix',
    then an array of indices of greatest fractional endmembers is obtained
    by argmax(mix).

    Note that depending on endmembers given, fractional abundances for
    endmembers may be negative.
    '''
    assert members.shape[1] == data.shape[2], \
        'Matrix dimensions are not aligned.'

    members = members.astype(float)
    # Calculate the pseudo inverse
    pi = np.dot(members, np.transpose(members))
    pi = np.dot(np.linalg.inv(pi), members) #hacked by rr, bug report sent

    (M, N, B) = data.shape
    unmixed = np.zeros((M, N, members.shape[0]), float)
    for i in range(M):
        for j in range(N):
            unmixed[i, j] = np.dot(pi, data[i, j].astype(float))
    return unmixed

And i can understand what it is doing (within my limited understanding of linear algebra), but I cannot fathom the \ character following the line assert members.shape[1] == data.shape[2], \ .

Upvotes: 1

Views: 38

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