[R] noob requesting help

[Rui Barradas]

Hello,

Now the output of str() says 'dat' is a list not a data.frame. That's 
why R is complaining about dimensions (lack of, in this case).

Try

dat2 <- data.frame(do.call(cbind, dat), stringsAsFactors=FALSE)

Then run the lapply()

Also, if dput(head(dat, 20)) is very big, ommit the argument 20. See 
?head for its meaning.
But if the above works there's no need for it.

Rui Barradas

Em 14-06-2012 01:06, capital_P escreveu:
> Rui Barradas wrote
>> Sorry, but the output of dput() starts with 'structure', not like what
>> you've posted.
>> And there are much more than 20 dates in the beginning.
>>
>> The posting guide is easy to find
>>
> apologies for my earlier ignorance.
>
> It seems the output of dput(head(data, 20) is too big to print in full. When
> I press stop immediately after pressing enter, I get:
>
> dput(head(long, 30))
> structure(list(tripID = c(3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L,
> 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L,
> 3L, 3L, 3L, 3L, 3L), device_info_serial = c(121L, 121L, 121L,
> 121L, 121L, 121L, 121L, 121L, 121L, 121L, 121L, 121L, 121L, 121L,
> 121L, 121L, 121L, 121L, 121L, 121L, 121L, 121L, 121L, 121L, 121L,
> 121L, 121L, 121L, 121L, 121L), mdate = structure(c(33L, 33L,
> 33L, 33L, 33L, 33L, 33L, 33L, 33L, 33L, 33L, 33L, 33L, 33L, 33L,
>
> If I let it run just a little bit longer, it gives the enormous output like
> before.
>
> I made a new vector containing only the columns I need for this problem:
>
>> str(dat)
> List of 4
>   $ device_info_serial: int [1:34773] 121 121 121 121 121 121 121 121 121 121
> ...
>   $ hour              : int [1:34773] 10 11 11 11 11 11 11 11 11 11 ...
>   $ time              : POSIXlt[1:34773], format: "2009-05-21 10:59:24" ...
>   $ tripID            : int [1:34773] 3 3 3 3 3 3 3 3 3 3 ...
>
> You were right about the factors. I think I solved it using:
>
> dat$time<- strptime(long$date_time.x, format = "%Y-%m-%d %H:%M:%S")
>
> this seems to help, as R doesn't start computing for hours. It does give an
> error though:
>
>> departures<- lapply(split(dat, list(dat$device_info_serial, dat$tripID)),
>> function(x) x[x$time == min(x$time),])
> Error in x[x$time == min(x$time), ] : incorrect number of dimensions
> In addition: Warning messages:
> 1: In split.default(dat, list(dat$device_info_serial, dat$tripID)) :
>    data length is not a multiple of split variable
> 2: In min(x$time) : no non-missing arguments to min; returning Inf
>
> --
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>
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