bpy27. Counting Letters of a biological sequence

We use the createRecords function, that we had used in the last example, by using an appropriate import.

We also define a new function, count, which will count unique letters and return their number of occurrences. This function, in turn, can be used by other modules if they import it.

In the function count, we try to add 1 to number already there, for the appropriate dictionary entry. Should that entry not exist, it is created and set to 1.

# bpy27.py
from __future__ import print_function, division
from bpy26 import createRecords

def count(seq):
    count = {}
    for i in seq:
        try: count[i] = count[i] + 1
        except: count[i] = 1
    return count
    
if __name__ == '__main__':
    records = createRecords('data')
    for record in records:
        print('Entry Name:',record.entry_name)
        print('Sequence counts:')
        print(count(record.sequence))

#Entry Name: IGF1R_HUMAN
#Sequence counts:
#{'A': 72, 'C': 44, 'E': 113, 'D': 62, 'G': 91, 'F': 47,
# 'I': 73, 'H': 23, 'K': 69, 'M': 39, 'L': 116, 'N': 85,
# 'Q': 35, 'P': 81, 'S': 97, 'R': 80, 'T': 69, 'W': 21,
# 'V': 87, 'Y': 63}
#Entry Name: IGF1R_MOUSE
#Sequence counts:
#{'A': 68, 'C': 44, 'E': 114, 'D': 63, 'G': 91, 'F': 48,
# 'I': 73, 'H': 24, 'K': 67, 'M': 40, 'L': 115, 'N': 87,
# 'Q': 36, 'P': 83, 'S': 92, 'R': 82, 'T': 73, 'W': 22,
# 'V': 90, 'Y': 61}