hwb-tnsi.py

#!/usr/bin/env python
def is_function(d):
    """Takes a dictionary and determines if function"""
    for k,v in d.items():
        if len(v) == 0:
            # Not a Function if No Output for Input
            return False
        if len(v) > 1:
            # Not a Function if Input has Multiple Output
            return False
    return True

def is_injective(d):
    used = []
    # Is function?
    if(is_function(d)):
        for k in d.items():
            if k[1] in used:
                return False
            else:
                used.append(k[1])
        return True
    else:
        return False

def is_surjective(d):
    # Put values in comparison list
    lrange = []
    # codomain list
    codomain = [0,1,2,3,4,5,6,7,8,9]
    # Is function?
    if(is_function(d)):
        # put all items into range
        for k,v in d.items():
            lrange.append(v.pop())
        # sort range
        lrange.sort()
        # remove dupes
        lrange = list(set(lrange))
        if lrange == codomain:
            return True
        else:
            return False
    else:
        return False