python课后作业1

from __future__ import division
fasta_file =open('D:/learningsources/python/managepython/5-seq.fa.txt','r+')
out_file =open('D:/learningsources/python/managepython/frq.txt','w+')
AA_dic = {}.fromkeys(['A','R','D','C','Q','E','H','I','G','N','L','K','M','F','P','S','T','W','Y','V'],0)
AA = 'ARDCQEHIGNLKMFPSTWYV'
seq=''
AC=''
for line in fasta_file:
    if line[0] =='>' and seq =='':
        AC=line
        out_file.write(AC)
    elif line[0] !='>' and seq == '':
        seq=line
        L=len(seq)
        for a in AA:
            AA_dic[a] = seq.count(a)     
        for k,v in AA_dic.items():
            out_file.write("%s %s %5.4f " % (k,':',v/L)+'\t')
        out_file.write('\n')
        seq=''           
out_file.close()