[R] Best way to do temporal joins in R?

[Edith Mertz]

Hi, I'm new to R-help mailing list and novice in R, so pls excuse 'silly
questions' and obvious blunders.

I have the same problem as Jon Greenberg (just different data) and have been
trying to use the code given above, but with some difficulty.

Pls Help?

My data:

Table 1 (TideH.csv)
Date	        Time	        Tide Height
03/02/2010	08:00:00	1.9
03/02/2010	09:00:00	1.49
03/02/2010	10:00:00	1.04

Table 2 (Fix times.csv)
Station	Date	        Time	        Fix Type
1	        03/02/2010	09:20:30	Mn
1	        03/02/2010	09:23:27	Mn
1	        03/02/2010	09:32:05	Mn

Need to get tide height values /nearest/ to the fix time.
Result should be:

Station	Date	        Time	        Fix Type  Tide Height
1	        03/02/2010	09:20:30	Mn            1.49
1	        03/02/2010	09:23:27	Mn            1.49
1	        03/02/2010	09:32:05	Mn            1.04

This is what I have tried so far:

library(chron)
TideH <- read.csv("TideH.csv")

TideH[,"Date"] <- as.character(TideH[,"Date"])
TideH[,"Date"] <- as.Date(TideH[,"Date"],format="%d/%m/%Y")
TideH[,"Time"] <- as.character(TideH[,"Time"])
TideH[,"Tide.Height"] <- as.numeric(TideH[,"Tide.Height"])

TideH$dt <- as.chron(paste(TideH$date, TideH$time), "%Y%m%d %H%M%S")

Error in `$<-.data.frame`(`*tmp*`, "dt", value = numeric(0)) : 
  replacement has 0 rows, data has 3

What went wrong?

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