[R] Printing a variable in a loop

[Miguel Manese]

Hi Kat,

On Thu, Jun 28, 2012 at 8:22 AM, kat_the_great <knv4 at hotmail.com> wrote:
> Dear R Users:
>
> I'm a STATA user converting to R, and I'd like to be to do the following.
> #Assign var_1 and var_2 a value
> 10->var1
> 20->var2
>
> #Now I'd like to print the values of var_1 and var_2 by looping through
> var_1 and var_2 in such a manner:
>
> while(y<3){
>  print(var_y)
> y+1->y
> }

The nearest you can get is

while (y < 3) {
  print(.GlobalEnv[[paste("var", y, sep="")]])
  y <- y + 1
}

.GlobalEnv (a list, or strictly speaking an environment) contains all
variables at the top-level of the REPL

But this is not how we do it in R.

1. if you want to "display" the variable, just type it

> var1

2. In Stata, you are working with one (tabular) data set at any time.
In R, you can work with multiple data sets (R construct: dataframes)
at the same time. For example using the builtin anscombe data set

Stata:

use anscombe
di x1 y1 x2 y2   // display all
di x1 y1 x2 y2 if _n <= 10


R:

# data(anscombe)           # optional
anscombe[, c("x1", "y1", "x2", "y2")]   # index by column
anscombe[1:10, c("x1", "y1", "x2", "y2")]  # index by row & column
head(anscombe[, c("x1","y1","x2","y2")], n=10]   # same as above




Regards,

Jon