[R] creating a variable using concatenation
Steve Chen
steve at stat.tku.edu.tw
Wed Mar 31 05:15:07 CEST 2010
You can try this:
library(tutoR)
plot(eval.string(toplot))
Steve Chen
On 2010/3/31 上午 09:24, zubin wrote:
> A general problem i run into, i know there must be a simple solution.
>
> I like to create a variable by appending a 1 for example, (i need to
> loop later on from 1 to X, thus the reason for this). So i assign the
> variable vplot with this value, however it has quotes and when i use it
> in a barplot, it throws an error. but the tcenter$X1 does exist, its an
> element of a data frame. So if i type directly it works, but i like to
> do this programmatically, as i have to generate a bunch of these plots
> and need to loop.
>
> So how do i concatenate to create a variable, then reference that
> variable in a function call?
>
>
> R> x<- data.frame(1,2,3,4,5,6,7,8)
> R> x
> X1 X2 X3 X4 X5 X6 X7 X8
> 1 1 2 3 4 5 6 7 8
> R> x$X1
> [1] 1
>
> R> i=1
> R> toplot<- paste("x$X",i,sep="")
> R> toplot
> [1] "x$X1"
>
> okay lets test:
>
> R> plot(x$X1)
> -it works i see the plot
>
> however this DOES not work
>
> R> plot(toplot)
>
> Error in plot.window(...) : need finite 'ylim' values
> In addition: Warning messages:
> 1: In xy.coords(x, y, xlabel, ylabel, log) : NAs introduced by coercion
> 2: In min(x) : no non-missing arguments to min; returning Inf
> 3: In max(x) : no non-missing arguments to max; returning -Inf
>
>
> Thus, that's my problem, i know it must be simple - the variable is equal to x$X1 but it does not work in a function call? i tried many functions - always some type of error.
>
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