Storing a collection of integers in a list

Question

I have a list containing RNA base letters and a dictionary to convert them to numeric values. What I am trying to do is store these numeric values into a new list. I have:

RNA_list = ['C', 'G', 'A', 'U']
RNA_dictionary = {'A': 1, 'U': 2, 'C': 3, 'G': 4}
for i in RNA_list:
    if i in RNA_dictionary:
        RNA_integers = RNA_dictionary[i]
    else:
        print()

So RNA_integers is 3, 4, 1, 2, but I need to store them in a list somehow. I wanted to do something like:

RNA_integer_list = []
for i in RNA_integers:
    RNA_integer_list = RNA_integer_list + i

But that results in an error because the for loop can't iterate over the integers. I'm new to Python so I'm not sure how to approach this. If anyone else can help me, I'd really appreciate it!

Answer 1

You can do

RNA_list = ['C', 'G', 'A', 'U']
RNA_dictionary = {'A': 1, 'U': 2, 'C': 3, 'G': 4}
RNA_integers = []
for i in RNA_list:
    if i in RNA_dictionary:
        RNA_integers.append (RNA_dictionary[i])

print RNA_integers

Output

[3, 4, 1, 2]

Or using list comprehension

RNA_integers = [RNA_dictionary[i] for i in RNA_list if i in RNA_dictionary]

Answer 2

Or you can use map:

map(RNA_dictionary.get, RNA_list)