list question

[python101]

I would like to write a program count the items that appear in BOTH list
[code=python]
A=['A', 'B', 'C','D', 'F','G', 'H']
B=['FF', 'GG', 'A','B', 'DD','EE', 'GG']

for i in range(len(A)):
count=0
for k in range(len(B)):
if A[i]==B[k]:
count+=1

count
[/code]
the result is 0 but it should be 2 (for 'A' and 'B')
What did I do wrong?

[dazzler]

What did I do wrong?

you put the count=0 in the wrong place ;)

[code=python]
A=['A', 'B', 'C','D', 'F','G', 'H']
B=['FF', 'GG', 'A','B', 'DD','EE', 'GG']

count=0
for i in range(len(A)):
for k in range(len(B)):
if A[i]==B[k]:
count+=1

print count
[/code]

[rogerlew]

How about this:
[code=python]
count=0
for a in A:
if a in B: count+=1
print count
[/code]
or this:
[code=python]
count=sum([1 for a in A if a in B])
print count
[/code]

[ghostdog74]

>>> A=['A', 'B', 'C','D', 'F','G', 'H']
>>> B=['FF', 'GG', 'A','B', 'DD','EE', 'GG']
>>> A+B
['A', 'B', 'C', 'D', 'F', 'G', 'H', 'FF', 'GG', 'A', 'B', 'DD', 'EE', 'GG']
>>> (A+B).count("A")
2
>>> (A+B).count("B")
2
>>>

[rogerlew]

>>> A=['A', 'B', 'C','D', 'F','G', 'H']
>>> B=['FF', 'GG', 'A','B', 'DD','EE', 'GG']
>>> A+B
['A', 'B', 'C', 'D', 'F', 'G', 'H', 'FF', 'GG', 'A', 'B', 'DD', 'EE', 'GG']
>>> (A+B).count("A")
2
>>> (A+B).count("B")
2
>>>

Neat trick, but Python101 is looking for a method of counting items common to both lists.

[ghostdog74]

Neat trick, but Python101 is looking for a method of counting items common to both lists.

yes, my bad. wrong interpretation.