练习(二)计算以下序列的GC含量(知识点:float、count):ATTCTTTCTTCCAAACCTCTTCAATTATATCTGTTTAATTCCCTCTTTCTTTGTCTGAAAACAATTAATA
#python
>>> x='ATTCTTTCTTCCAAACCTCTTCAATTATATCTGTTTAATTCCCTCTTTCTTTGTCTGAAAACAATTAATA'
>>> g=x.count('G')
>>> c=x.count('C')
>>> length=len(x)
>>> percent=float(g+c)/length
>>> percent
0.2676056338028169
练习(三)计算1~100(含100)所有偶数的和，脚本保存为sum.py(知识点:循环语句、判断语
句)
vim sum.py
n=1
sum=0
while n <= 100:
n = n+1
if n%2 == 0:
sum = sum+n
print(sum)
练习(四)获得以下序列的反向互补序列，并保存为reverse_complement.py文件(知识点:循环
语句、判断语句或字典):ATTCTTTCTTCCAAACCNTCTTCAATTATATCTGTTTAATTCCCTCTTTCTTTGTCTGAAAACAATTAATA
vim reverse_complement.py
seq = 'ATTCTTTCTTCCAAACCNTCTTCAATTATATCTGTTTAATTCCCTCTTTCTTTGTCTGAAAACAATTAATA'
reverse_seq =''
dict = {'A':'T','T':'A','C':'G','G':'C','N':'N'}
for i in seq:
reverse_seq =dict[i] + reverse_seq
print(reverse_seq)
