Using read.zoo instead of read.table and zoo()?

Question

I have a file with many rows of this kind

2010-01-12 19:40   1021.00000   0.00001     1.00
2010-01-12 19:50   1031.00000   0.00000     -1.00

In order to read it as zoo I use

tmp <- read.table("myfile")
GOEMD <- zoo(tmp[,3], as.chron(paste(tmp[,1],tmp[,2]), format="%Y-%m-%d %H:%M"))

that works properly But I'd like to use read.zoo() instead.

I've tried

f <- function(x)  as.chron(paste(tmp[,1],tmp[,2]))
tmp <- read.zoo("myfile", index = 1:2, sep=" ", FUN  = f)

and even specifying

colClasses= c("character","character","numeric","numeric","numeric")

but it doesn't work; it says: line 136 (the one I've pasted above) doesn't have 14 elements.

I've also tried:

tmp <- read.zoo("myfile", index = 1:2, sep=" ", FUN  = as.chron)

Answer 1

1. The typo in f was already pointed out.
2. Also there are a few features of read.zoo that you might wish to take advantage of. Firstly, note that if the value of the index argument is a list then the columns referenced in each component of that list are passed as separate arguments to FUN. Also note that a FUN2 argument is available which is applied to the output of FUN so we can write it in a compact fashion like this:

Thus try this:

library(zoo)
library(chron)

Lines <- "2010-01-12 19:40   1021.00000   0.00001     1.00
2010-01-12 19:50   1031.00000   0.00000     -1.00"

z <- read.zoo(textConnection(Lines), index = list(1, 2), 
        FUN = paste, FUN2 = as.chron)

The above was written to be self contained so you could just copy it verbatim to the clipboard and then paste it into your R session. To use it with your file replace textConnection(Lines) with "myfile".

Answer 2

Your function f has to search for tmp. You probably intended:

f <- function(x)  as.chron(paste(x[,1],x[,2]))
tmp <- read.zoo("myfile", index = 1:2, sep=" ", FUN = f)

Also, the sample data you posted looks like it's tab-delimited, not space-delimited, so you may need to this instead:

tmp <- read.zoo("myfile", index = 1, sep="\t", FUN = as.chron)