Convert data frame with date column to timeseries

Question

I\'ve got a data frame with the following data:

>PRICE
         DATE  CLOSE
1    20070103 54.700
2    20070104 54.770
3    20070105 55.120
4    20070108 5         


        

Answer 1

This answer based on @Joshua_Ulrich's answer creates a time series from the built-in airquality dataset containing "Daily air quality measurements in New York, May to September 1973".

> head(airquality,3)
  Ozone Solar.R Wind Temp Month Day
1    41     190  7.4   67     5   1
2    36     118  8.0   72     5   2
3    12     149 12.6   74     5   3

Convert Month and Day to a vector of class "Date"

airqualitydate = as.Date(sprintf("1973%02.0f%02.0f", airquality$Month, airquality$Day), 
                         format="%Y%m%d")

Create the time series object

ts_airquality <- xts(airquality, airqualitydate)
head(ts_airquality, 3)
           Ozone Solar.R Wind Temp Month Day
1973-05-01    41     190  7.4   67     5   1
1973-05-02    36     118  8.0   72     5   2
1973-05-03    12     149 12.6   74     5   3

Plot to illustrate the different output of the plot.xts() function. (compare to plot(airquality))

plot(ts_airquality$Ozone, main="Ozone (ppb)")
lines(ts_airquality$Temp, on=NA, main="Temperature (degrees F)")

Note, the base R ts() method is mostly suited for quarterly or yearly data. As explained in an answer to "starting a daily time series in R":

"Time Series Object does not work well with creating daily time series. I will suggest you use the zoo library."

In particular the xts package is an extension to zoo.