Question

I am reading time series data CSV into an R data frame, using the read.csv function

I am then converting the date column (column 1) as follows:

mydata[,1] <- as.Date(mydata[,1])

I want to know how to:

1. Sort the data in the data frame by date (ascending or descending)
2. Once the data is sorted, I would like to use the dates as an index into the data frame, to fetch a row of data (i.e. an observation set for that date. How may I do this?

Answer 1

Assuming you have a time series of numbers indexed by unique dates, read.zoo in the zoo package does most of that. Read the 5 vignettes that comes with it as well as ?read.zoo and in particular the zoo-read vignette.