"""
elements in common to two lists

turn lists into sets and find intersection

min (a.count(x), b.count(x))


---
sets have no duplicates, lists can
lists have order, sets don't

===
key is email address, value is # messages sent
loop over file updating dictionary


"""

def count(list,elt):
	x = 0
	for p in list:
		if p == elt: x += 1
	return x



def update(email):
	global info
	info[email] = info.get(email,0) + 1

def update(email):
	global info
	if not email in info.keys():
		info[email] = 0
	info[email] += 1





"""
red
blue
aqua
--

aqua
brown
magenta
white

-
[(1,5),(2,6), (3,7), (4,8)]

combo = zip(x,y)

--
[(1,5),(1,6),(1,7),(1,8)
 (2,5),(2,6),(2,7),(2,8)
 (3,5),(3,6),(3,7),(3,8)
 (4,5),(4,6),(4,7),(4,8)
]


[x for x in range(500,601)]

[0,3,6,9,12,15,18,21,...]
[3*x for x in range(0,34)]
[x for x in range(0,100,3)]
[x for x in range(0,100) if x % 3 == 0]
[x**2 for x in range(0,501) if x**2 < 500]

[x*x for x in range(0,23)]

#here's a recipe for developing a list comprehension
[]                      #step 1
[x for x in words]      #step 2
[exp(x) for x in words] #if the new list has related/not same elements
[x for x in words if something] # if new list has different # elements

[x for x in words if commonCount(x,"snipe") == 3]


def maxDistance(points):
	md = 0
	for p in points:
		for q in points:
			current = distance(p,q)
                        if md < current:
			    md = current
	return md



alternative with list comprehension:
max([distance(a,b) for a in points for b in points])


"""
for last, file problem
"""


clubs = {}

def readFile(filename):
	file = open(filename)
	global clubs

	for line in file:
		parts = line.split(",")
		name = parts[0]

		for id in parts[1:]:
			if not id in clubs:
				clubs[id] = []
			clubs[id].append(name)

	file.close()

"""
[netid for netid in clubs if len(clubs[netid]) > 3]

"""

def mostMembers(clubs):
	"""
	return name of club with most members
	"""
        mName = ""
        mValue = 0

        names = set()
        local = {}          #dictionary for club counts

        for studOrgs in clubs.values():
            for org in studOrgs:
                if not org in local:
                    local[org] = 0       # not seen before 
                local[org] += 1
		if local[org] > mValue:
                    mValue = local[org]
                    mName = org

        return mName