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?
help appreciated.
/iaw
---
ivo welch
paste / system mystery
4 messages · ivo_welch-rstat8303@mailblocks.com, Thomas Lumley, Douglas Bates +1 more
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
On 8/15/05, ivo_welch-rstat8303 at mailblocks.com
<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?
Poor understanding but the mistake is a common one. If you want to form a character vector of length 1 you must use the "collapse" argument to paste(). Try
eargs <- 3:5
paste("echo A B", paste(eargs, collapse = " "))
[1] "echo A B 3 4 5"
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?
Feature:
The arguments of paste() get pasted, and you have just specified one
argument which is a character *vector*.
You want to say that the elements of the vector should be pasted as follows:
line <- paste(c("echo A B", eargs), collapse = " ")
Uwe Ligges
help appreciated. /iaw --- ivo welch
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