How to flatten only some dimensions of a numpy array

Is there a quick way to "sub-flatten" or flatten only some of the first dimensions in a numpy array?

For example, given a numpy array of dimensions (50,100,25), the resultant dimensions would be (5000,25)

Take a look at numpy.reshape .

    >>> arr = numpy.zeros((50,100,25))
    >>> arr.shape
    # (50, 100, 25)

    >>> new_arr = arr.reshape(5000,25)
    >>> new_arr.shape   
    # (5000, 25)

    # One shape dimension can be -1. 
    # In this case, the value is inferred from 
    # the length of the array and remaining dimensions.
    >>> another_arr = arr.reshape(-1, arr.shape[-1])
    >>> another_arr.shape
    # (5000, 25)

From: stackoverflow.com/q/18757742