Hi I am purely new to python and numpy.. I am using python for doing statistical calculations to Climate data.. I have a data set in the following format.. Year Jan feb Mar Apr................. Dec 1900 1000 1001 , , , 1901 1011 1012 , , , 1902 1009 1007 , , ,,,, , ' , , , ,,,, , , 2010 1008 1002 , , , I actually want to standardize each of these values with corresponding standard deviations for each monthly data column.. I have found out the standard deviations for each column.. but now i need to find the standared deviation only for a prescribed mean value ie, when i am finding the standared deviation for the January data column.. the mean should be calculated only for the january data, say from 1950-1970. With this mean i want to calculate the SD for entire column. Any help will be appreciated..