def index_of_coincidence_avg(self,text,modulosize):
        icmodouloarr = []
        columnstr = ""
        sumnum = 0
        for i in range (0,modulosize):
            columnstr = ""
            for j in range(i,len(text),modulosize):
                columnstr+=text[j]
            icmodouloarr.append(self.index_of_coincidence(columnstr))

        sumnum = sum(icmodouloarr)
        return sumnum/modulosize

    def find_len_of_key(self,text):
        maxlen=0
        avgOfAllKeys = []
        if(len(text)<15):
            maxlen=len(text)
        else:
            maxlen=15
        avgOfAllKeys=[]
        for i in range(1,maxlen):
            avgOfAllKeys.append(self.index_of_coincidence_avg(text,i))

        return min(avgOfAllKeys)