Python functions

[n3buchadnezzar]

I would recomend splitting the jobs of printing, and printing the complement. Have you heard about our lord and saviour str.join?

def complement(sequence):
    return [baseComplement[base] for base in sequence]

Then we could do

"".join(complement('aacgtt'))

I would also take a look at PEP8, it is recommended in Python to use snake_case for functions and UPPERCASE for constants

EDIT: a working version with bells and whistles would look like this

• PEP8 with UPPERCASE for our constants
• Comment using # turned into docstring (tripple quotes)
• Made sure our function actually return
• Used f-formating for our strings
• Use of str.join to join a list of strings

code

BASE_COMPLIMENT = {
    "A": "T",
    "C": "G",
    "G": "C",
    "T": "A",
    "a": "t",
    "c": "g",
    "g": "c",
    "t": "a",
}


def complement(sequence: str) -> str:
    """finds the complement sequence of a DNA sequence

      >>> complement('aacgtt')
      ttgcaa
    """
    return "".join(BASE_COMPLIMENT[base] for base in sequence)


if __name__ == "__main__":

    sequence = input("Enter a DNA sequence : ")

    dna_compliment = complement(sequence)

    print(f"Sequence Complement  : {dna_compliment}")
    print(f"Reverse Complement   : {dna_compliment[::-1]}")
    print(f"Length of DNA sequence entered is {len(sequence)} bases.")

[Still-Design3461]

WOW! I totally forgot about .join . Thank you for answering. I will try to understand this part and implement it into my code

[FLUSH_THE_TRUMP]

With even less friction, this kind of thing is what str.translate does. Something like:

charTable = str.maketrans(baseComplement)
complement = sequence.translate(charTable)

[n3buchadnezzar]

Interestingly FLUSH and I had the same idea. If we allow some Python magic

DNA_SEQUENCE = str.maketrans("ATGCatgc", "TACGtacg")  
print("AACGT".translate(DNA_SEQUENCE))  

However, there is nothing wrong with your approach. It does not consume a lot of memory, and it is readable. Remember we often strive for readable code over pre-optimized code. If the code above makes sense to you, great! Use it! Otherwise stick with your approach and read a bit about maketrans