CODEWITHSUNDEEP
python
ValquirionAce
ValquirionAce

Reputation: 21

Reverse function not entirely replacing everything

Write a function ReverseComplement to solve the Reverse Complement Problem, which is reproduced below. (Hint: use the function reverse that you wrote on the last step as a subroutine.)

Need a little help here! I need to change a given text not only backwards but also making some letters equal to others in order to generate a whole new result:

def reverse(text):
        reversed_text = ""
    # Note: Indices are starting with zero and the last number in ranges aren't included
    for i in range(len(text)):   
        reversed_text += text[len(text)-1-i]
    return reversed_text

text = 'AGCTTTTCATTCTGACTGCAACGGGCAATATGTCTCTGTGTGGATTAAAAAAAGAGTGTCTGATAGCAGC'
text = text.replace('A', 'T')
text = text.replace('G', 'C')

So my output would print:

CCTCCTTTCTCTCTCTCTTTTTTTTTTCCTCTCTCTCTCTTTTTCCCCCTTCCTCTCTCTTTCTTTTCCT

But the real thing that I need to do whit my function is:

GCTGCTATCAGACACTCTTTTTTTAATCCACACAGAGACATATTGCCCGTTGCAGTCAGAATGAAAAGCT

Not entirely replacing the A for T and G for C.... I have 0 programming experience and I`m stuck! please Help

Upvotes: 1

Views: 93

Answers (3)

BernardoGO
BernardoGO

Reputation: 1856

First, you can reverse the whole string by using:

def reverse(string):
    return string[::-1]

or

''.join(reversed("AGCTTTTCATTCTGACTGCAACGGGCAATATGTCTCTGTGTGGATTAAAAAAAGAGTGTCTGATAGCAGC"))

Then, you'll need to replace the letters

text.replace('A', 'T') will replace all 'A' with 'Ts. So TAT -> TTT. What you need to do is text.replace('A', '1'), text.replace('T', 'A'), text.replace('1', 'T').

example:

text = 'AGCTTTTCATTCTGACTGCAACGGGCAATATGTCTCTGTGTGGATTAAAAAAAGAGTGTCTGATAGCAGC'
# For swapping A and T
text.replace("A", "1")
text.replace("T", "A")
text.replace("1", "T")

# For swapping G and C
text.replace("G", "1")
text.replace("C", "G")
text.replace("1", "C")

Upvotes: 2

PK123
PK123

Reputation: 53

In Python, the easiest way to reverse a string would be

text = "ACGT"
reversed_text = text[::-1]
# Now, reversed_text is "TGCA"

Once you've done that, you can replace A with T and C with G (and vice-versa)

# For swapping A and T
reversed_text.replace("A", "1")
reversed_text.replace("T", "A")
reversed_text.replace("1", "T")

# For swapping G and C
reversed_text.replace("G", "1")
reversed_text.replace("C", "G")
reversed_text.replace("1", "C")

Upvotes: 0

Robby Cornelissen
Robby Cornelissen

Reputation: 97247

Here's one way to do it:

text[::-1].translate(maketrans('ACGT', 'TGCA'))

This uses:

  • text[::-1] to reverse the string
  • maketrans to create a translation table
  • translate to perform the actual translation

Snippet for Python 2:

from string import maketrans

text = 'AGCTTTTCATTCTGACTGCAACGGGCAATATGTCTCTGTGTGGATTAAAAAAAGAGTGTCTGATAGCAGC'
translated = text[::-1].translate(maketrans('ACGT', 'TGCA'))

print(translated)

Snippet for Python 3:

text = 'AGCTTTTCATTCTGACTGCAACGGGCAATATGTCTCTGTGTGGATTAAAAAAAGAGTGTCTGATAGCAGC'
translated = text[::-1].translate(str.maketrans('ACGT', 'TGCA'))

print(translated)

Upvotes: 4

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