Re: [Rd] extract function [ and empty index
Beware x[TRUE] returns the same as x[] only if x is NOT a zero-length vector (at least until R 2.5.1): numeric(0)[] numeric(0) numeric(0)[TRUE] [1] NA Enrique -Original Message- -- Message: 7 Date: Mon, 10 Mar 2008 02:29:32 +0800 From: Laurent Gautier [EMAIL PROTECTED] Subject: Re: [Rd] extract function [ and empty index To: Gabor Grothendieck [EMAIL PROTECTED] Cc: r-devel@r-project.org Message-ID: [EMAIL PROTECTED] Content-Type: text/plain; charset=ISO-8859-1 Thanks, I was forgetting the recycling rule. L. 2008/3/9, Gabor Grothendieck [EMAIL PROTECTED]: Use TRUE. On Sun, Mar 9, 2008 at 5:05 AM, Laurent Gautier [EMAIL PROTECTED] wrote: Dear list, I am having a question regarding the extract function [. The man page says that one usage with k-dimensional arrays is to specify k indices to [, with an empty index indicating that all entries in that dimension are selected. The question is the following: is there an R object qualifying as an empty index ? I understand that the lazy evaluation of parameters allows one to have genuinely missing parameters, but I would like to have an object instead. I understand that one can always have an if/else workaround, but I thought should ask, just in case. I tried with NULL but with little success, as it appears to give the same results as an empty vector. m = matrix(1, 2, 2) m[1, NULL] numeric(0) m[1, integer(0)] numeric(0) Since I was at it, I noted that the result obtained with numeric(0) definitely makes sense but could as well be seen as challenging the concept of an empty index presented in the man page (One could somehow expect the presence of an object meaning everything rather than missingness meaning it). Thanks, Laurent __ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel -- __ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
[Rd] extract function [ and empty index
Dear list, I am having a question regarding the extract function [. The man page says that one usage with k-dimensional arrays is to specify k indices to [, with an empty index indicating that all entries in that dimension are selected. The question is the following: is there an R object qualifying as an empty index ? I understand that the lazy evaluation of parameters allows one to have genuinely missing parameters, but I would like to have an object instead. I understand that one can always have an if/else workaround, but I thought should ask, just in case. I tried with NULL but with little success, as it appears to give the same results as an empty vector. m = matrix(1, 2, 2) m[1, NULL] numeric(0) m[1, integer(0)] numeric(0) Since I was at it, I noted that the result obtained with numeric(0) definitely makes sense but could as well be seen as challenging the concept of an empty index presented in the man page (One could somehow expect the presence of an object meaning everything rather than missingness meaning it). Thanks, Laurent __ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
Re: [Rd] extract function [ and empty index
Use TRUE. On Sun, Mar 9, 2008 at 5:05 AM, Laurent Gautier [EMAIL PROTECTED] wrote: Dear list, I am having a question regarding the extract function [. The man page says that one usage with k-dimensional arrays is to specify k indices to [, with an empty index indicating that all entries in that dimension are selected. The question is the following: is there an R object qualifying as an empty index ? I understand that the lazy evaluation of parameters allows one to have genuinely missing parameters, but I would like to have an object instead. I understand that one can always have an if/else workaround, but I thought should ask, just in case. I tried with NULL but with little success, as it appears to give the same results as an empty vector. m = matrix(1, 2, 2) m[1, NULL] numeric(0) m[1, integer(0)] numeric(0) Since I was at it, I noted that the result obtained with numeric(0) definitely makes sense but could as well be seen as challenging the concept of an empty index presented in the man page (One could somehow expect the presence of an object meaning everything rather than missingness meaning it). Thanks, Laurent __ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel __ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
Re: [Rd] extract function [ and empty index
Thanks, I was forgetting the recycling rule. L. 2008/3/9, Gabor Grothendieck [EMAIL PROTECTED]: Use TRUE. On Sun, Mar 9, 2008 at 5:05 AM, Laurent Gautier [EMAIL PROTECTED] wrote: Dear list, I am having a question regarding the extract function [. The man page says that one usage with k-dimensional arrays is to specify k indices to [, with an empty index indicating that all entries in that dimension are selected. The question is the following: is there an R object qualifying as an empty index ? I understand that the lazy evaluation of parameters allows one to have genuinely missing parameters, but I would like to have an object instead. I understand that one can always have an if/else workaround, but I thought should ask, just in case. I tried with NULL but with little success, as it appears to give the same results as an empty vector. m = matrix(1, 2, 2) m[1, NULL] numeric(0) m[1, integer(0)] numeric(0) Since I was at it, I noted that the result obtained with numeric(0) definitely makes sense but could as well be seen as challenging the concept of an empty index presented in the man page (One could somehow expect the presence of an object meaning everything rather than missingness meaning it). Thanks, Laurent __ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel -- -BEGIN PGP SIGNATURE- Version: GnuPG v1.4.6 (GNU/Linux) iEYEARECAAYFAkYgwJ4ACgkQB/w/MLoyRDeQlgCeMp8v69/Wy24Q4IaBVhoG1M5R 2h4AoIOTvKbrFpTklRDjV7u8tEOeSQqt =JPph -END PGP SIGNATURE- __ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
