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pythonnumpydimensions

Unwanted extra dimensions in NumPy array


I've opened a .fits image:

scaled_flat1 = pyfits.open('scaled_flat1.fit')   
scaled_flat1a = scaled_flat1[0].data

and when I print its shape:

print scaled_flat1a.shape

I get the following:

(1, 1, 510, 765)

I want it to read:

(510, 765)

How do I get rid of the two ones before it?


Solution

  • There is the method called squeeze which does just what you want:

    Remove single-dimensional entries from the shape of an array.

    Parameters

    a : array_like
        Input data.
    axis : None or int or tuple of ints, optional
        .. versionadded:: 1.7.0
    
        Selects a subset of the single-dimensional entries in the
        shape. If an axis is selected with shape entry greater than
        one, an error is raised.
    

    Returns

    squeezed : ndarray
        The input array, but with with all or a subset of the
        dimensions of length 1 removed. This is always `a` itself
        or a view into `a`.
    

    for example:

    import numpy as np
    
    extra_dims = np.random.randint(0, 10, (1, 1, 5, 7))
    minimal_dims = extra_dims.squeeze()
    
    print minimal_dims.shape
    # (5, 7)