[R] Applying strptime() to a data set or array

[Andrew Athan]

A$date is already a string, as read from the file.  I tried it anyway, 
for you...

 > A$date<-strptime(as.character(A$date),"%Y-%m-%d %H:%M:%s")
Error in "$<-.data.frame"(`*tmp*`, "date", value = list(sec = c(0, 0,  :
        replacement has 9 rows, data has 3198
 >

A.

Jacques VESLOT wrote:
> maybe you need to transform A$date to character:
> A$date <- strptime(as.character(A$date), ...)
>
> see also:
> ?ISOdatetime
>
> Andrew Athan a écrit :
>
>> I'm sure this is just the result of a basic misunderstanding of the 
>> syntax of R, but I am stumped.
>>
>> A <- 
>> read.table(file="sumByThirtyMinute.csv",sep=",",col.names=c("date","pandl")) 
>>
>>
>> A now consists of thousands of rows, but A$date is a string...
>> ...
>> 3183 2006-02-28 12:00:00    548.470
>> 3184 2006-02-28 12:30:00    515.240
>> 3185 2006-02-28 13:00:00    140.120
>> 3186 2006-02-28 13:30:00    450.940
>> 3187 2006-02-28 14:00:00    318.570
>> ...
>>
>>
>>
>>
>> So, I try to convert A$date to a POSIXlt ...
>>
>> A[,1]<-strptime(A$date,"%Y-%m-%d %H:%M:%s")
>> A$date<-strptime(A$date,"%Y-%m-%d %H:%M:%s")
>>
>>
>> which gives me a warning that the length of the array I am trying to 
>> replace A$date with is 9 ... but if I print strptime(A$date,"%Y-%m-%d 
>> %H:%M:%s"), it clearly has thousands of rows.  Yet, if I ask for 
>> length(strptime(A$date,"%Y-%m-%d %H:%M:%s")), I get 9.
>>
>> What am I doing wrong?  Do I need to convert the return value of 
>> strptime(A$date,"%Y-%m-%d %H:%M:%s") to some array/vector/matrix 
>> datatype before attempting to assign it?
>>
>> Thanks,
>> Andrew
>>
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>>
>