def mean(dataList):
    """Calculates the mean average of a list of numbers.
    
    @type dataList: list
    @param dataList: input data, must be a one dimensional list
    @rtype: float
    @return: mean average
    
    """
    sum=0
    for item in dataList:
        sum=sum+float(item)
    if len(dataList)>0:
        mean=sum/float(len(dataList))
    else:
        mean=0
    return mean