[R] Date Time Conversion problems...

[Petr Pikal]

Hi

On 4 Feb 2004 at 8:31, Shawn Way wrote:

> At one time (version 1.7), the code below used to work for converting
> and extracting based on the Date Time.  In version 1.8.1, something
> changed I know, but I cannot for the life of me figure out what...
> 
> Data:
> 
> UserName,RequestDate,PO,OrderDate,ExpDelivDate,Vendor,Total
> "Woody, Jim",12/19/2002,AP15063,1/7/2003,2/10/2003,Ames ,8570
> "Harrold, Paul",12/31/2002,AP15083,1/9/2003,1/10/2003,Ryan ,1039.5
> "Vo, Hoang",12/27/2002,AP15055,1/6/2003,1/13/2003,TIDEA,1005.36 "Way,
> Shawn",1/2/2003,AP15043,1/2/2003,1/9/2003,JS   ,1000 "Vo,
> Hoang",1/7/2003,SO17440,1/8/2003,12/31/2003,USFi-,3705 "Harrold,
> Paul",1/10/2003,AP15122,1/13/2003,1/14/2003,FishM,65.06
> 
> Old Code:
> 
> library(lattice)
> data <- read.csv("h:\\list3.csv",header=TRUE)
> data2 <-
> data.frame(Name=data$UserName,Date=data$RequestDate,Vendor=data$Vendor
> ,Cost= data$Total) data2$Date <-
> strptime(as.character(data2$Date),format="%m/%d/%Y") start <-
> strptime(c("1/01/2003"),format="%m/%d/%Y") end <-
> strptime(c("12/31/2003"),format="%m/%d/%Y") data3 <- data2[data2$Date
> >= start & data2$Date <= end,] lset(col.whitebg())
> xyplot(Cost~as.POSIXct(Date)|Name,data=data3,
>        xlab="Date",
>        ylab="PO Cost($)",
>        ylim=c(0,10000),
>        panel= function(x,y){
>          a <- mean(y)
>          panel.grid(h=-1,v=2)
>          panel.xyplot(x,y)
>          panel.abline(h=a,col="red")
>        }
>        )
> 
> The error I get is from line 4, 
> 
> > data2$Date <- strptime(as.character(data2$Date),format="%m/%d/%Y")
> Error in "$<-.data.frame"(`*tmp*`, "Date", value =
> strptime(as.character(data2$Date),  : 
>  replacement has 9 rows, data has 230

most probably you have POSIXlt format

try

length(strptime(as.character(data2$Date),format="%m/%d/%Y"))
should result 9

you have to change to POSIXct through as.POSIXct

andd you than get lengthof your date vector to be correct.

Cheers
Petr



> 
> This used to work for replacing the dates with POSIX values...
> 
> Also of interest is the extraction for data3, is this the correct
> method for extraction?
> 
> What I'm looking at is the spending habits of individuals...
> 
> Thanks for your help...
> 
>   _____  
> 
> "Don't rush me, you rush a miracle, you get a rotten miracle." 
> -Miracle Max, The Princess Bride
> 
>   _____  
> 
>   Shawn Way, PE	 Tanox, Inc.	
> Engineering Manager	 10301 Stella Link	
> sway at tanox.com	 Houston, TX 77025
> 
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Petr Pikal
petr.pikal at precheza.cz