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.
