[R] efficiency

[Uwe Ligges]

jimi adams wrote:
> 
> i previously sent in the message below
> and i got several responses back, that work, however, now i am running into
> a different problem
> i used the following line to read in the file:
> 
> temp.file<- readLines("2.75.0.997.1")
> 
> i was then recommended to use:
> 
> lapply(strsplit(temp.file,"*", as.numeric)
> 
> to convert this to a list
> the only problem is that the file that i am reading in has values ranging
> from 1:10000, and this splits it out into individual numeric characters...
> not the initial values (e.g., 876 returns as 8, 7, & 6)
> i think i figured out how to do this if the values were all of the same
> length, but they are not, so i am wondering if there is some sort of split
> command that is equivalent to what sep="" does when writing...rather than
> being defined by a specific numeric value.
> 
> ultimately what i want is:
> if the initial file which looks like:
> 1 412 2000
> 2 4
> 3 8888
> ...
> 
> to become a list:
> [1]
> 412 2000
> [2]
> 4
> [3]
> 8888
> ...
> 
> thanks in advance.


 lapply(strsplit(temp.file, " "), function(x) as.numeric(x)[-1])


Uwe Ligges



> ***************************
> i have a set of  files that i am reading into R one at a time and applying
> to a function that i have written
> where each is a 'table' n (columns) x 10000 (rows)
> n varies across the files and most of the rows only have data in the first
> few columns
> currently i am reading them in with the command:
> read.table(file="2.75.0.997.1", header=FALSE, sep="", skip=13, fill=,
> row.names=1, nrows=10000)->list
> 
> ***and it works fine
> however we are now working with a huge table.
> i was wondering if there is a more efficient way to read this in
> 
> IDEALLY i would like to have it as a list where each element is a row from
> the input file, eliminating all of the NA's that the above approach results
> in , such that i would have a list with 10000 elements and each of variable
> length from 1:n
> 
> any help greatly appreciated
> jimi adams
> Department of Sociology
> The Ohio State University
> 300 Bricker Hall
> 190 N. Oval Mall
> Columbus, OH 43210-1353
> 614-688-4261
> 
> our mind has a remarkable ability to think of contents as being independent
> of the act of thinking
>                                              -georg simmel
> 
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