[R] Loading in Large Dataset + variables via loop

[Rui Barradas]

Hello,

Right, it should be 'varNames' in the apply. I guess I had something 
called colNames in my environment. I've just rm(list=ls()) and rerun the 
code, corrected. No errors this time.

varNames is the result of expand.grid, therefore does have a dim attribute.

The faulty instruction corrected is:

varNames <- as.vector(apply(varNames, 1, paste, collapse=""))

Rui Barradas

Em 15-07-2012 18:12, arun escreveu:
> Hi Rui,
>
> Getting some error messages:
>
>
> varNames <- as.vector(apply(colNames, 1, paste, collapse=""))
> Error in apply(colNames, 1, paste, collapse = "") :
>    dim(X) must have a positive length
>
> A.K.
>
>
>
> ----- Original Message -----
> From: Rui Barradas <ruipbarradas at sapo.pt>
> To: cmc0605 <colose21 at gmail.com>
> Cc: r-help at r-project.org
> Sent: Sunday, July 15, 2012 8:12 AM
> Subject: Re: [R] Loading in Large Dataset + variables via loop
>
> Hello,
>
> Why do you need 9 variables in your environment if they are time series
> that correspond to the same period? You should use time series functions.
>
> #install.packages('zoo')
> library(zoo)
>
> # Make up a dataset
> Year <- seq(from=as.Date("1901-01-01"), by="year", length.out=100)
> dat <- data.frame(matrix(rnorm(100*9), ncol=9), Year)
>
> # assign names.
> varNames <- expand.grid(c("temp", "precip", "pressure"), 1:3,
> stringsAsFactors=FALSE)
> varNames <- as.vector(apply(colNames, 1, paste, collapse=""))
> varNames <- c(varNames, "Year")
> names(dat) <- varNames
> head(dat)
>
> # and transform it into a time series of class 'zoo'
> z <- zoo(dat[, 1:9], order.by=dat$Year)
> str(z)
> head(z)
>
>
> Another way would be, like you say, to use a loop to put the variables
> in a list. Something like
>
> lst <- list()
> for(i in 1:9) lst[[i]] <- dat[, i]
> names(lst) <- varNames
>
>
> Note that I've used a dataset called 'dat' n place of your 'A'. You
> should post a data example, like the posting guide says. Using dput().
>
> Hope this helps,
>
> Rui Barradas
>
>
>
> Em 14-07-2012 03:44, cmc0605 escreveu:
>> Hello, I'm new to R with a (probably elementary) question.
>>
>> Suppose I have a dataset called /A/ with /n/ locations, and each location
>> contains within it 3 time series of different variables (all of 100 years
>> length); each time series is of a weather variable (for each location there
>> is a temperature, precipitation, and pressure).  For instance, location 1
>> has a temperature1 time series, a precip1 time series, and a pressure1 time
>> series; location two has a temperature2, precip2, and pressure2
>> timeseries...That is, there are 100 rows, and (/n/*3)+1 columns.  The extra
>> column is the time.
>>
>> I want to load in this dataset and declare a variable for each time series.
>> The columns are in order of location, so it goes temp1, precip1,pressure1,
>> temp2,... and so forth in increasing column order.  There are always 100
>> rows.  Manually, Id have to do:
>>
>> temp1=A[,1]
>> precip1=A[,2]
>> pressure1=A[,3]
>> temp2=A[,4]
>> precip2=A[,5]
>> pressure2=A[,6]
>> temp3=A[,7]
>> and so forth.....
>>
>> Problem is, n is large, so I don't want to repeat this pattern forever.  I
>> figure I need a loop both for the variable name (ie.., the variable at a
>> particular location) as well as for what column it reads from.
>>
>> Any help...?
>>
>>
>>
>> --
>> View this message in context: http://r.789695.n4.nabble.com/Loading-in-Large-Dataset-variables-via-loop-tp4636501.html
>> Sent from the R help mailing list archive at Nabble.com.
>>
>> ______________________________________________
>> R-help at r-project.org mailing list
>> https://stat.ethz.ch/mailman/listinfo/r-help
>> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
>> and provide commented, minimal, self-contained, reproducible code.
>>
>
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>