Import a library into a program using import libraryname.
 
        
        Use the numpy library to work with arrays in Python.
 
        
        The expression array.shape gives the shape of an array.
 
        
        Use array[x, y] to select a single element from a 2D array.
 
        
        Array indices start at 0, not 1.
 
        
        Use low:high to specify a slice that includes the indices from low to high-1.
 
        
        Use # some kind of explanation to add comments to programs.
 
        
        Use numpy.mean(array), numpy.max(array), and numpy.min(array) to calculate simple statistics.
 
        
        Use numpy.mean(array, axis=0) or numpy.mean(array, axis=1) to calculate statistics across the specified axis.