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表1   空气质量指数(AQI)划分标准

图a

图b

f=open("日均 AQI.csv","r")

grade={"优":0,"良":0,"轻度污染":0,"中度污染":0,"重度污染":0,"严重污染":0}

for line in f:

       a=line.split(",")   #列表a数据格式形如['11 月7 日', '41.17', '63.75']

       t=float(_____)

       if t<=50:

             key="优"

       elif t<=100:

             key="良"

       elif t<=150:

             key="轻度污染"

       elif t<=200:

             key="中度污染"

       elif t<=300:

             key="重度污染"

       grade[key]+=1

print("本周共有"+str(grade["优"])+"天的空气质量为优")