python类属性与全局变量

我在一个类中定义了一个属性(yyear),并使用一个全局变量(year)来初始化它。 当我在类中调用该方法时,它正在更新全局变量,即使我没有给它赋值。 为什么会这样?是的。 错误是对类变量定义的错误位置做了一些处理。

JAN = MAR =MAY =JUL =AUG= OCT =DEC=[0]*31
APR=JUN=SEP=NOV=[0]*30
FEB=[0]*28

YEAR = [JAN, FEB, MAR, APR, MAY, JUN, JUL, AUG, SEP, OCT, NOV, DEC]

class load:
    yYEAR=YEAR
    def __init__(self, DURATION, LTYPE):
        self.DURATION=DURATION
        self.LTYPE= LTYPE


    def daily247(self):
        if self.LTYPE==1 :
            for month in range(len(self.yYEAR)):
                for day in range(len(self.yYEAR[month])):
                    self.yYEAR[month][day]= 1
            else:
                self.yYEAR= YEAR
        self.dispLoad()     

    def dispLoad(self):
        print(self.yYEAR[0])
        print(self.yYEAR[1])

event1= load(10,1)
event1.daily247() # Expected result ones in all nested elements in YEAR

event2= load(10,0)
event2.daily247()  # Expected result zeros in all nested elements in YEAR
print(YEAR[1])  # expected result is to have zeros for all elements