Miscellany

def mean_and_stdev(list):
	mean=sum(list)/len(list)
	sdsq = sum([(i - mean) ** 2 for i in list])
        stdev = (sdsq / (len(list) )) ** .5
	return mean,stdev

def get_mean_and_stdev(list):
	mean,stdev=mean_and_stdev(list)
	maximal_typical_stdev=mean/2
	#removing outliers
	list=filter(lambda x:abs(x-mean)<maximal_typical_stdev,list)
	return mean_and_stdev(list)