How to apply avg function to DataFrame series monthly?
data.resample('M', how='mean')
I have a DataFrame series with day resolution. I want to transform the series to a series of monthly averages. Ofcourse I can apply rolling mean and select only every  30th of means but it would not precise. I want to get series which contains mean value from the previous month on every first day of a month. For example, on February 1 I want to have daily average for the January. How can I do this in pythonic way?