CheckIO - Home Challenge 9 : Min and Max

checkio.1.09.MinAndMax.py

# CheckIO - Home Challenge 9 : Min and Max
# http://checkio.org

# In this mission you should write you own py3 realisation of the built-in functions min and max. 
# Some builtin functions are closed here: import, eval, exec, globals. 
# Don't forget you should realize two functions in your code.
#   max(iterable, *[, key]) or min(iterable, *[, key])
#   max(arg1, arg2, *args[, key]) or min(arg1, arg2, *args[, key])
# Return the largest (smallest) item in an iterable or the largest(smallest) of two or more arguments.
# If one positional argument is provided, it should be an iterable. 
# The largest (smallest) item in the iterable is returned. 
# If two or more positional arguments are provided, the largest (smallest) of the positional arguments is returned.
# The optional keyword-only key argument specifies a function of one argument 
# that is used to extract a comparison key from each list element (for example, key=str.lower).
# If multiple items are maximal (minimal), the function returns the first one encountered.
# -- Python Documentation (Built-in Functions - https://docs.python.org/3.3/library/functions.html)
# Input: One positional argument as an iterable or two or more positional arguments. Optional keyword argument as a function.
# Output: The largest item for the "max" function and the smallest for the "min" function.
# Precondition: All test cases are correct and functions don't have to raise exceptions.
    
def minSimple(arg1, arg2, key):
    if key!=None and key(arg1)<key(arg2) or key==None and arg1<arg2: return arg1
    return arg2
    
def min(*args, **kwargs):

    key=kwargs.get("key", None)         # Extracting key
    if len(args)==1: args=list(args[0]) # Adapting arguments
        
    # Comparing arguments, one by one
    result=args[0]
    for x in range(1,len(args)):
        result=minSimple(result,args[x],key)
    return result


def maxSimple(arg1, arg2, key):
    if key!=None and key(arg2)>key(arg1) or key==None and arg2>arg1: return arg2
    return arg1
    
def max(*args, **kwargs):
    
    key=kwargs.get("key", None)         # Extracting key
    if len(args)==1: args=list(args[0]) # Adapting arguments
        
    # Comparing arguments, one by one
    result=args[0]
    for x in range(1,len(args)):
        result=maxSimple(result,args[x],key)
    return result


if __name__ == '__main__':
    #These "asserts" using only for self-checking and not necessary for auto-testing
    assert max(3, 2) == 3, "Simple case max"
    assert min(3, 2) == 2, "Simple case min"
    assert max([1, 2, 0, 3, 4]) == 4, "From a list"
    assert min("hello") == "e", "From string"
    assert max(2.2, 5.6, 5.9, key=int) == 5.6, "Two maximal items"
    assert min([[1, 2], [3, 4], [9, 0]], key=lambda x: x[1]) == [9, 0], "lambda key"
    assert min(abs(i) for i in range(-10, 10)) == 0