Question

How do I count CAG number in DNA using python? please provide an example!

Answer 1

Code for count "CAG" in DNA sequence is as below. In case of any query, do comment.

#function to count CAG in DNA sequence

def count_CAG_In_DNA(dnaSequence):

   

    countOfCAG = 0

    #do-while loop to parse the while DNA sequence

    while True:

        #find the position of CAG in DNA sequence

        positionOfCAG = dnaSequence.find("CAG")

       

        #if no CAG found then break the loop

        if (positionOfCAG == -1):

            break

        #increment the count of CAG

        countOfCAG += 1

        #extract the new array,slicing array from the character till CAG is found

        dnaSequence = dnaSequence[positionOfCAG+3:]

    return countOfCAG

   

# main driver function

#output should be 2

dnaSequence = "TACAGCAGC"

print("Count of CAG in DNA Squence :" + dnaSequence)

print(count_CAG_In_DNA(dnaSequence))

#output should be 0

dnaSequence ="TACATCATC"

print("Count of CAG in DNA Squence :" + dnaSequence)

print(count_CAG_In_DNA(dnaSequence))

#output should be 6

dnaSequence = "TACAGCAGCTACAGCAGCTACAGCAGC"

print("Count of CAG in DNA Squence :" + dnaSequence)

print(count_CAG_In_DNA(dnaSequence))

#output should be 9

dnaSequence = "TACAGCAGCTACAGCAGCTACAGCAGCTACAGCAGCTACAGC"

print("Count of CAG in DNA Squence :" + dnaSequence)

print(count_CAG_In_DNA(dnaSequence))

#output should be 7

dnaSequence ="TACAGCAGCTACAGCTACAGCAGCTACAGCAGC"

print("Count of CAG in DNA Squence :" + dnaSequence)

print(count_CAG_In_DNA(dnaSequence))

#===========================================Screen shot of code ==============

Screen shot of the code for indentation:

Output:

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