在Python中更改计数器的输出

Question

I'm using the following code to unzip a dictionary and count the values at each site:

result = [Counter(site) for site in zip(*myDict.values())]

The output looks something like: Counter({'A': 74}), Counter({'G': 72, 'C': 2}) There are five possible values: A, T, G, C , and N

I only want the counter to spit out a value if one of the five values is less than 74. So for the above example, only the second would be outputted. How do you use an if statement within the counter? Furthermore, how can I label each site, so that above it could just say:

Site 2: 'G': 72, 'C': 2

myDict looks like this:

{'abc123': ATGGAGGACGACT, 'def332': ATGCATTGACGC}

Except there are 74 entries. Each value is the same length. Basically, I don't know how to use a counter that can give me an output for when each site of each value doesn't match up. So for the sequences above, the 4th site does not match. I want the counter to output the following:

site 4: 'G': 1, 'C': 1

Answer 1

You can use enumerate to index the sites and the most_common method on Counter can be used to check if the count is < 74. Here's an example with just two strings:

from collections import Counter
myDict = {'a':'ATGTTCN','b':'ATTTCCG'}
result = [(i,Counter(site)) for i,site in enumerate(zip(*myDict.values()))]
result = [x for x in result if x[1].most_common()[0][1] < 2]
for site,count in result:
    print 'Site {}: {}'.format(site,str(count)[9:-2])

Output:

Site 2: 'T': 1, 'G': 1
Site 4: 'C': 1, 'T': 1
Site 6: 'G': 1, 'N': 1

Answer 2

using Dict Comprehension and only storing values if max(Counter(x).values())<74 , use enumerate() to get the Site number.

>>> mydict={'abc123': 'ATGGAGGACGACT', 'def332': 'ATGCATTGACGC'}
>>> result={'Site {}'.format(i+1):Counter(x) for i,x in enumerate(zip(*mydict.values())) if max(Counter(x).values())<2}
>>> result
{'Site 7': Counter({'T': 1, 'G': 1}), 'Site 6': Counter({'T': 1, 'G': 1}), 'Site 4': Counter({'C': 1, 'G': 1}), 'Site 9': Counter({'A': 1, 'C': 1}), 'Site 8': Counter({'A': 1, 'G': 1}), 'Site 11': Counter({'A': 1, 'G': 1}), 'Site 10': Counter({'C': 1, 'G': 1})}

or convert Counter to dict :

>>> {'Site {}'.format(i+1):dict(Counter(x)) for i,x in enumerate(zip(*mydict.values())) if max(Counter(x).values())<2}

{'Site 7': {'T': 1, 'G': 1}, 'Site 6': {'T': 1, 'G': 1}, 'Site 4': {'C': 1, 'G': 1}, 'Site 9': {'A': 1, 'C': 1}, 'Site 8': {'A': 1, 'G': 1}, 'Site 11': {'A': 1, 'G': 1}, 'Site 10': {'C': 1, 'G': 1}}