[R] Optimize code to read text-file with digits

[Martin Møller Skarbiniks Pedersen]

On 8 September 2017 at 11:25, PIKAL Petr <petr.pikal at precheza.cz> wrote:

> > Moller Skarbiniks Pedersen

> My program which is slow looks like this:
> >
> > filename <- "digits.txt"
> > lines <- readLines(filename)
>
> why you do not read a file as a whole e.g. by
>
> lines<-read.table("digits.txt")
>

Good idea.

>
> And now I am lost.


[...]


>  Or do you want one big numeric vector from all your numbers?

here you need to read values as character variables
>

Yes. That's what I am looking for.

>
> lines<-read.table("digits.txt", colClasses="character")
> numbers<-as.numeric(unlist(strsplit(as.character(lines[1,]),"")))
> changes first row to numeric vector.
>
>
Do I still need to loop through all lines?
It is maybe even slower now.

numbers <- vector('numeric')
for (i in 1:nrows(lines)) {
  numbers <- c(numbers, as.numeric(unlist(strsplit(as.
character(lines[i,]),""))))
}


> Anyway, can you explain what is your final goal?
>
>
A numeric vector of length 1 million. Each element should be one digit.


> Cheers
> Petr
>
>
Thanks.
/Martin

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