从R数据框中提取过去30天的全天数据

Question

I am totally new to R environment and I'm stuck at Date operations. The scenario is, I have a daily database of customer activity of a certain Store, and I need to extract last 30 months data starting from current date. In other words, suppose today is 18-NOV-2014, I need all the data from 18-OCT-2014 till today in a separate data-frame. To extract it, what kind of iteration logic should I write in R?

Answer 1

You don't need an iteration. What you could do is, assuming your data.frame is called X, and the date column, DATE, you could write:

X$DATE=as.Date(X$DATE, format='%d-%B-%Y')

the 'format' argument is to match your date format you specify in you question. Then, to get the lines you are interested in, something like:

X[X$DATE>=as.Date(today(),format='%d-%B-%Y')-30)]

which is all the lines that are after today - 30 days. Does this help at all?