CODEWITHSUNDEEP
pythondictionarypython-2.x
Jacob Hancock
Jacob Hancock

Reputation: 39

Picking complementary base pairs with python

I'm trying to develop a program where the users inputs a string of nucleotides and is given the complementary string (CAGT become GTCA, for example).

I've set up a dictionary:

dicto = {'A':'T', 'C':'G', 'T':'A', 'G':'C'}

And I'm inputting user input in the form of a string to cross-reference with dictionary keys:

user = raw_input(prompt)

But, despite searching, I can't figure out how to how to use the multiple characters input by the user against the dictionary. I imagine it will be something like the below:

print dicto[x for x in user]

Any help is welcome.

Upvotes: 0

Views: 498

Answers (3)

BeatButton
BeatButton

Reputation: 121

For this, using str.translate would be appropriate. Like so:

#!python2
import string
trans = string.maketrans("ACTG", "TGAC")
user = raw_input()
print user.translate(trans)

#!python3
trans = str.maketrans('ACTG', 'TGAC')
user = input()
print(user.translate(trans))

Upvotes: 3

loreson
loreson

Reputation: 31

You can use

print("".join([dicto[x] for x in user]))

What this does: Create a list with the right base pairs, looked up in dicto:

[dicto[x] for x in user]

And feed this list to "".join() which creates a single string, by inserting the string it is called on between all List elements (empty string here, space is a common option)

Upvotes: 0

chepner
chepner

Reputation: 532418

You can use operator.itemgetter.

>>> dicto = {'A':'T', 'C':'G', 'T':'A', 'G':'C'}
>>> user = 'ACTG'
>>> from operator import itemgetter
>>> itemgetter(*user)(dicto)
('T', 'G', 'A', 'C')
>>> ''.join(_)
'TGAC'

Upvotes: 0

Related Questions