Set of python functions for checking list of number increasing

monotonic.py

def strictly_increasing(L):
    """Returns TRUE if the values in the list are strictly increasing
    Always increasing; never remaining constant or decreasing or null.
    """ 
    return all(x<y for x, y in zip(L, L[1:]))


def strictly_decreasing(L):
    """Returns TRUE if the values in the list are strictly decreasing
    Always decreasing; never remaining constant or increasing or null.
    """ 
    return all(x>y for x, y in zip(L, L[1:]))
  
  def non_decreasing(L):
    """Returns TRUE if values in the list are increasing.
    Allows for values remaining constant. Does NOT allow null
    """
    return all(x<=y for x, y in zip(L, L[1:]))


def non_increasing(L):
    """Returns TRUE if values in the list are decreasing.
    Allows for values remaining constant. Does NOT allow null
    """
    return all(x>=y for x, y in zip(L, L[1:]))


def not_strictly_increasing(L):
    # strip leading null values
    while len(L)!=0 and L[0] is None: L.pop(0)
    # check list has monotonically increasing values
    # this returns TRUE if values are increasing
    strictly_increasing = all(x<y for x, y in zip(L, L[1:]))
    # invert the return value
    return not(strictly_increasing)