Here is a vector
a <- c(TRUE, FALSE, FALSE, NA, FALSE, TRUE, NA, FALSE, TRUE)
I'd like a simple function that returns TRUE
everytime there is a TRUE
in "a", and FALSE
everytime there is a FALSE
or a NA
in "a".
The three following things do not work
a == TRUE identical(TRUE, a) isTRUE(a)
Here is a solution
a[-which(is.na(a))]
but it doesn't seem to be a straightforward and easy solution
Is there another solution ?
Here are some functions (and operators) I know:
identical() isTRUE() is.na() na.rm() & | !
What are the other functions (operators, tips, whatever,...) that are useful to deal with TRUE
, FALSE
, NA
, NaN
?
What are the differences between NA
and NaN
?
Are there other "logical things" than TRUE
, FALSE
, NA
and NaN
?
Thanks a lot !
The && and || Operators in JavaScript. If applied to boolean values, the && operator only returns true when both of its operands are true (and false in all other cases), while the || operator only returns false when both of its operands are false (and true in all other cases).
In other words NA & TRUE evaluates to NA, but NA & FALSE evaluates to FALSE.
In programming languages value of True is considered as 1. whereas false is zero. therefore In Boolean algebra True + False=1+0=1.
The is.na() is a built-in R function that returns TRUE if it finds NA value and FALSE if it does not find in the dataset. If the value is NA, the is.na() function returns TRUE, otherwise, returns FALSE.
You don't need to wrap anything in a function - the following works
a = c(T,F,NA) a %in% TRUE [1] TRUE FALSE FALSE
To answer your questions in order:
1) The ==
operator does indeed not treat NA's as you would expect it to. A very useful function is this compareNA
function from r-cookbook.com:
compareNA <- function(v1,v2) { # This function returns TRUE wherever elements are the same, including NA's, # and false everywhere else. same <- (v1 == v2) | (is.na(v1) & is.na(v2)) same[is.na(same)] <- FALSE return(same) }
2) NA stands for "Not available", and is not the same as the general NaN ("not a number"). NA is generally used for a default value for a number to stand in for missing data; NaN's are normally generated because a numerical issue (taking log of -1 or similar).
3) I'm not really sure what you mean by "logical things"--many different data types, including numeric vectors, can be used as input to logical operators. You might want to try reading the R logical operators page: http://stat.ethz.ch/R-manual/R-patched/library/base/html/Logic.html.
Hope this helps!
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