Hi everyone The following behavior (in R 3.6.1 and R-devel r77040) caught me by surprise today: truthy <- c(TRUE, FALSE) falsy <- c(FALSE, TRUE, FALSE) if (truthy) "check" #> Warning in if (truthy) "check": the condition has length > 1 and only the #> first element will be used #> [1] "check" if (falsy) "check" #> Warning in if (falsy) "check": the condition has length > 1 and only the #> first element will be used if (FALSE || truthy) "check" #> [1] "check" if (FALSE || falsy) "check" if (truthy || FALSE) "check" #> [1] "check" if (falsy || FALSE) "check" The || operator gobbles the warning about a length > 1 vector. I wonder if the existing checks for length 1 can be extended to the operands of the || and && operators. Thanks (and apologies if this has been raised before). Best regards Kirill
Check length of logical vector also for operands of || and &&?
3 messages · Kirill Müller, Henrik Bengtsson, Duncan Murdoch
NEWS for R 3.6.0: * Experimentally, setting environment variable _R_CHECK_LENGTH_1_LOGIC2_ will lead to warnings (or errors if the variable is set to a ?true? value) when && or || encounter and use arguments of length more than one.
Sys.setenv("_R_CHECK_LENGTH_1_LOGIC2_" = "TRUE")
if (FALSE || truthy) "check"
Error in FALSE || truthy : 'length(x) = 2 > 1' in coercion to 'logical(1)' Some more info and breadcrumbs at https://github.com/HenrikBengtsson/Wishlist-for-R/issues/48 /Henrik
On Mon, Aug 19, 2019 at 4:19 PM Kirill M?ller <krlmlr+ml at mailbox.org> wrote:
Hi everyone The following behavior (in R 3.6.1 and R-devel r77040) caught me by surprise today: truthy <- c(TRUE, FALSE) falsy <- c(FALSE, TRUE, FALSE) if (truthy) "check" #> Warning in if (truthy) "check": the condition has length > 1 and only the #> first element will be used #> [1] "check" if (falsy) "check" #> Warning in if (falsy) "check": the condition has length > 1 and only the #> first element will be used if (FALSE || truthy) "check" #> [1] "check" if (FALSE || falsy) "check" if (truthy || FALSE) "check" #> [1] "check" if (falsy || FALSE) "check" The || operator gobbles the warning about a length > 1 vector. I wonder if the existing checks for length 1 can be extended to the operands of the || and && operators. Thanks (and apologies if this has been raised before). Best regards Kirill
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On 19/08/2019 10:19 a.m., Kirill M?ller wrote:
Hi everyone The following behavior (in R 3.6.1 and R-devel r77040) caught me by surprise today: truthy <- c(TRUE, FALSE) falsy <- c(FALSE, TRUE, FALSE) if (truthy) "check" #> Warning in if (truthy) "check": the condition has length > 1 and only the #> first element will be used #> [1] "check" if (falsy) "check" #> Warning in if (falsy) "check": the condition has length > 1 and only the #> first element will be used if (FALSE || truthy) "check" #> [1] "check" if (FALSE || falsy) "check" if (truthy || FALSE) "check" #> [1] "check" if (falsy || FALSE) "check" The || operator gobbles the warning about a length > 1 vector. I wonder if the existing checks for length 1 can be extended to the operands of the || and && operators. Thanks (and apologies if this has been raised before).
This seems to be an August topic. It was discussed last year in a long thread starting with this message: https://stat.ethz.ch/pipermail/r-devel/2018-August/076678.html I think there was general agreement that it would be a good idea to add some warnings. News for R 3.6.0 includes this: "Experimentally, setting environment variable _R_CHECK_LENGTH_1_LOGIC2_ will lead to warnings (or errors if the variable is set to a ?true? value) when && or || encounter and use arguments of length more than one." You get a warning if you set that variable to "warn", you get an error if you set it to "true". Duncan Murdoch Duncan Murdoch