[R] How to format data for time-series analysis

B. Bogart bbogart at sfu.ca
Mon Oct 29 00:11:57 CET 2007


Hey all again,

So I'm going through tutorials and getting a better sense of R structures.

So I made some mockup data to see if I can figure out how to load it
properly. (attached) if anyone has any suggestions on a better way to
structure that data please let me know.

So the file has three columns, the date/time of the event, the event
name, the event state (if there is one) and the event value (if there is
one). I'm using the built-in date/time class of openoffice as a starting
point for the date/time.

I'm expecting to load this file as a data.frame where each column is a
different class. Like so:

  > data <-
read.table(file="testdata.csv",sep=",",header=TRUE,colClasses=c("zoo","factor","factor","numeric"))

Unfortunately It seems there is no function for converting from
"character" to "zoo":

Error in methods::as(data[[i]], colClasses[i]) :
         no method or default for coercing "character" to "zoo"

So I tried using POSIXct as suggested.

Which does load the file, but it seems the times are truncated, leaving
only the dates:

  > data
        Time Event State Value
1  24-10-20   BMU          20
2  25-10-20 Image           2
...3  26-10-20   BMU          10
4  27-10-20   BMU          11
5  28-10-20 Image           3
6  29-10-20  DPMS Begin    NA
7  30-10-20 Dream Begin    NA
8  31-10-20   BMU           3
9   1-11-20 Image           4
10  2-11-20   BMU          50
11  3-11-20   BMU          20
12  4-11-20  DPMS   End    NA
13  5-11-20 Dream   End    NA

Same results as using "Date" as the colClass.

Any advice?

Thanks,
B. Bogart





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