I haven't followed this thread closely, but to your question I think maybe this is what you want"
> z <- c("","") > all(z == "") [1] TRUE > z <- c("a","") > all(z == "") [1] FALSE If this isn't it, just ignore without reply. Bert Gunter "The trouble with having an open mind is that people keep coming along and sticking things into it." -- Opus (aka Berkeley Breathed in his "Bloom County" comic strip ) On Thu, Sep 30, 2021 at 8:51 AM Luigi Marongiu <marongiu.lu...@gmail.com> wrote: > > Yes, but the && should work within `unique(df_b$q) == ""` because the > test should be: (IF THE DATAFRAME HAS ZERO ROW) OR (ALL THE ELEMENTS > OF $q ARE EMPTY) THEN (PRINT empty). > Can I collapse the TRUE FALSE of `unique(df_b$q) == ""`into a single FALSE? > > On Thu, Sep 30, 2021 at 4:28 PM Sarah Goslee <sarah.gos...@gmail.com> wrote: > > > > Hi, > > > > The OR operator you used is working as expected: || starts from the > > left and evaluates only enough of the options to determine the > > results. The first test is TRUE, so the result is TRUE. It sounds > > like you might actually want an AND operator, & or &&, which will only > > return TRUE if all elements are TRUE, > > > > More on logical operators: > > https://stat.ethz.ch/R-manual/R-devel/library/base/html/Logic.html > > > > Sarah > > > > On Thu, Sep 30, 2021 at 9:07 AM Luigi Marongiu <marongiu.lu...@gmail.com> > > wrote: > > > > > > Hello, > > > I have two data frames, each with three rows: > > > ``` > > > df_a <- data.frame(a = letters[1:3], b = LETTERS[1:3], q = c("", "", ""), > > > stringsAsFactors = FALSE) > > > df_b <- data.frame(a = letters[4:6], b = LETTERS[4:6], q = c("", "", > > > "1.5"), > > > stringsAsFactors = FALSE) > > > ``` > > > I need to test whether the dataframe has been selected and if there is > > > a value in the q column. I combined in the following test: > > > ``` > > > if (nrow(df_a) == 0 || unique(df_a$q) == "") { > > > print("empty") > > > } > > > if (nrow(df_b) == 0 || unique(df_b$q) == "") { > > > print("empty") > > > } > > > ``` > > > The test for df_a worked as expected: > > > ``` > > > > nrow(df_a) == 0 > > > [1] FALSE > > > > unique(df_a$q) == "" > > > [1] TRUE > > > > (nrow(df_a) == 0 || unique(df_a$q) == "") > > > [1] TRUE > > > > if (nrow(df_a) == 0 || unique(df_a$q) == "") { > > > + print("empty") > > > + } > > > [1] "empty" > > > ``` > > > but the one for df_b did not: > > > ``` > > > > nrow(df_b) == 0 > > > [1] FALSE > > > > unique(df_b$q) == "" > > > [1] TRUE FALSE > > > > (nrow(df_b) == 0 || unique(df_b$q) == "") > > > [1] TRUE > > > > unique(df_b$q) > > > [1] "" "1.5" > > > ``` > > > I say that it did not work because unique(df_b$q) IS NOT "", hence > > > `(nrow(df_b) == 0 || unique(df_b$q) == "")` should be FALSE, instead R > > > evaluated the first element of unique(df_b$q) == "", which is TRUE. > > > How can I properly implement a logic test on vectors? > > > Thank you > > > > > > ______________________________________________ > > > R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see > > > https://stat.ethz.ch/mailman/listinfo/r-help > > > PLEASE do read the posting guide > > > http://www.R-project.org/posting-guide.html > > > and provide commented, minimal, self-contained, reproducible code. > > > > > > > > -- > > Sarah Goslee (she/her) > > http://www.sarahgoslee.com > > > > -- > Best regards, > Luigi > > ______________________________________________ > R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide http://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code. ______________________________________________ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.