Using a dictionary i would like to have this string sequence ACCTAGCCCTA as {'AC': 1, &#03-CodePudding

Using a dictionary I would like to have the string sequence "ACCTAGCCCTA" as {'AC': 1, 'CC': 3, 'CT': 2, 'TA': 2, 'AG': 1, 'GC': 1} but my code gives me {'AC': 1, 'CC': 2, 'CT': 2, 'TA': 2, 'AG': 1, 'GC': 1}, only CC 2.

p = input(str("entrez une chaine de caractere"))
dic = {p[i:i 2] : p.count(p[i:i 2] ) for i in range(len(p)-1)}
print(dic)

Why is that and what do I need to change?

CodePudding user response：

Another approach with zip Counter,

In [1]: from collections import Counter

In [2]: s = 'ACCTAGCCCTA'

In [3]: dict(Counter(map(lambda x: x[0] x[1], zip(s,s[1:]))))
Out[3]: {'AC': 1, 'CC': 3, 'CT': 2, 'TA': 2, 'AG': 1, 'GC': 1}

CodePudding user response：

For an efficient solution, use collections.Counter and a generator expression:

s = 'ACCTAGCCCTA'

from collections import Counter

out = dict(Counter(s[i:i 2] for i in range(len(s)-1)))

Output:

{'AC': 1, 'CC': 3, 'CT': 2, 'TA': 2, 'AG': 1, 'GC': 1}

variant without import

out = {}
for i in range(len(s)-1):
    out[s[i:i 2]] = out.get(s[i:i 2], 0) 1

CodePudding user response：

There's actually an itertools recipe for this, but you have to install it:

In [41]: from more_itertools import sliding_window

In [42]: s = "ACCTAGCCCTA"

In [43]: from collections import Counter

In [44]: Counter(sliding_window(s,2))
Out[44]: 
Counter({('A', 'C'): 1,
         ('C', 'C'): 3,
         ('C', 'T'): 2,
         ('T', 'A'): 2,
         ('A', 'G'): 1,
         ('G', 'C'): 1})

In [45]: Counter(sliding_window(s,4))
Out[45]: 
Counter({('A', 'C', 'C', 'T'): 1,
         ('C', 'C', 'T', 'A'): 2,
         ('C', 'T', 'A', 'G'): 1,
         ('T', 'A', 'G', 'C'): 1,
         ('A', 'G', 'C', 'C'): 1,
         ('G', 'C', 'C', 'C'): 1,
         ('C', 'C', 'C', 'T'): 1})