Don't. This is a classic mistake by newcomers to R that leads to abysmal
performance. The best alternative is to compute one column at a time, so your
data frame should be initialized with the inputs to your calculations, and you
compute output columns as vector expressions of the inputs without looping. For
example
dta <- data.frame( X=1:10 )
dta$Y <- 2*dta$X+3
dta$clip <- dta$Y > 13
dta$Yc1 <- ifelse( dta$clip, 13, dta$Y )
The ifelse function computes both possible answers for every element of the
result and the chooses between them. If you would prefer to do those
computations only for selected rows then you can use indexed assignment:
dta$Yc2 <- dta$Y
dta$Yc2[dta$clip] <- 13
If you absolutely must compute your results in little chunks of rows (e.g. one
row at a time) then at least store them into a list as you go and collapse them
into one data frame all at once using, say, the sapply function. This avoids
allocating a whole sequence of data frames with sizes from 1:n, which is very
inefficient use of memory.
---------------------------------------------------------------------------
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Sent from my phone. Please excuse my brevity.
Anup khanal <za...@hotmail.com> wrote:
>
>Hi Experts, I am newbie in R. Could you please share your idea to
>create a stack with no value or zero value? Nrow=1,Ncol=1, Ncell=1, I
>aim to work with looping, I want to make a first layer with zero values
>to add other layers further. Thanks.
>Best Regards,
>..................Anup KhanalNorwegian Institute of science and
>Technology (NTNU)Trondheim, NorwayMob:(+47) 45174313
>
> [[alternative HTML version deleted]]
>
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>PLEASE do read the posting guide
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>and provide commented, minimal, self-contained, reproducible code.
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