ferest.py~

import math
def avg_list(list):
    total=0
    for x in range(len(list)):
        if type(list[x])==float or type(list[x])==int:
            total = total + list[x]
    return float(total/len(list))

def DP_list(list):
    total=0.0
    avg_lst=avg_list(list)
    for x in range(len(list)):
        if type(list[x])==float or type(list[x])==int:
            total = total + (list[x]-avg_lst)**2
    return float(math.sqrt(total/(len(list)-1.)))

def cor_list(list1,list2):
    avg_list1=avg_list(list1)
    avg_list2=avg_list(list2)
    DP_list1=DP_list(list1)
    DP_list2=DP_list(list2)
    total=0
    for x in range(len(list1)):
        if (type(list1[x])==float or type(list1[x]) == int) and (type(list2[x])==float or type(list2[x]) == int):
            total = total + ((list1[x]-avg_list1)*(list2[x]-avg_list2))
    cov_list= total / (len(list1)-1)
	else:
	    return 'no_data'
    try:
	return cov_list/(DP_list1*DP_list2)
    except ZeroDivisionError:    
	return '**'