Issue with recording STRs in memory (PSET6 - DNA)

Question

I'm trying to record the number of repetitions of each str in the sequence. I created a dictionary as below and another empty dict because i couldn't update a dict while iterating through it. But for some reason my value variable always returns 0 for every str. Any suggestions?

iterator = {     
    "AGATC": 0,
    "TTTTTTCT": 0,
    "AATG": 0,
    "TCTAG": 0,
    "GATA": 0,
    "TATC": 0,
    "GAAA": 0,
    "TCTG": 0
}

record = {
    
}      

for x in iterator:
    value = 0
    for i in range(0, len(sequence)):
        if sequence[i:len(x)] == x:
            value += 1
        elif sequence[i:len(x)] != x:
            value = 0
    record.update( {x : value} )   # wordFreqDic.update( {'before' : 23} )

print(record)

This is how it prints :

~/pset6/dna/ $ python dna.py databases/large.csv sequences/1.txt
{'AGATC': 0, 'TTTTTTCT': 0, 'AATG': 0, 'TCTAG': 0, 'GATA': 0, 'TATC': 0, 'GAAA': 0, 'TCTG': 0}

Answer 1

Consider this snippet:

sequence = "AGATCAGATCAGATC"
x = "AGATC"
i = 2
print(sequence[i:len(x)])     # this is your code
print(sequence[i:i+len(x)])   # this is probably what you want

It prints:

ATC
ATCAG

More information on indexing and slicing can be found here.

Also interesting: sequence.count(x)