people = [{'name': 'Mary', 'height': 160},{'name': 'Isla', 'height': 80},
{'name': 'Sam'}]
height=0
n=0
for i in range(len(people)):
if isinstance((people[i].get('height')),int):
n=n+1
height=people[i].get('height')+ height
else:
print('人员的平均身高为%s'% (height/n))
#过程性编程方式