[R] paste / system mystery

Thomas Lumley tlumley at u.washington.edu
Mon Aug 15 19:43:44 CEST 2005


On Mon, 15 Aug 2005 ivo_welch-rstat8303 at mailblocks.com wrote:

>
> Dear R wizards:
>
> under R-2.1.0:
>
> eargs <- 3:5;
> line <- paste(c("echo A B", eargs));
> cat("executing from R: '", line, "'\n");
> system(line);
>
> Oddly, only "A" and "B" are echoed, not the eargs.  I had hoped that
> line would be one string at this point, and for printing this seems to
> be true.  However, unlist(line) still gives me the 4 components.  It
> almost seems like the objects were not really pasted, but kept separate
> [perhaps to conserve memory]---which works internally, but not
> externally.
>
> Is this my poor understanding of R, an R "feature," or an R bug?
>

It's your understanding.  Look at the `collapse' argument to paste().

 	-thomas




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