What evaluates to True False in R

Question

For example  in Ruby  only nil and false are false   What is what in R   e g   5  TRUE and 5  FALSE both evaluate to FALSE   However  1  TRUE is TRUE  Is there any general rule as to what  objects  numbers  etc   evaluate to

User · Answer

T and TRUE are True  F and FALSE are False  T and F can be redefined  however  so you should only rely upon TRUE and FALSE  If you compare 0 to FALSE and 1 to TRUE  you will find that they are equal as well  so you might consider them to be True and False as well

User · Answer

If you think about it  comparing numbers to logical statements doesn t make much sense  However  since 0 is often associated with  Off  or  False  and 1 with  On  or  True   R has decided to allow 1    TRUE and 0    FALSE to both be true  Any other numeric-to-boolean comparison should yield false  unless it s something like 3 - 2    TRUE

User · Answer

This is documented on  logical  The pertinent section of which is   Details           TRUE    and    FALSE    are reserved words denoting logical constants      in the R language  whereas    T    and    F    are global variables whose      initial values set to these   All four are    logical 1     vectors        Logical vectors are coerced to integer vectors in contexts where a      numerical value is required  with    TRUE    being mapped to    1L             FALSE    to    0L    and    NA    to    NA integer        The second paragraph there explains the behaviour you are seeing  namely 5    1L and 5    0L respectively  which should both return FALSE  where as 1    1L and 0    0L should be TRUE for 1    TRUE and 0    FALSE respectively  I believe these are not testing what you want them to test  the comparison is on the basis of the numerical representation of TRUE and FALSE in R  i e  what numeric values they take when coerced to numeric   However  only TRUE is guaranteed to the be TRUE    gt  isTRUE TRUE   1  TRUE  gt  isTRUE 1   1  FALSE  gt  isTRUE T   1  TRUE  gt  T  lt - 2  gt  isTRUE T   1  FALSE   isTRUE is a wrapper for identical x  TRUE   and from  isTRUE we note   Details                isTRUE x     is an abbreviation of    identical TRUE  x      and so is      true if and only if    x    is a length-one logical vector whose only      element is    TRUE    and which has no attributes  not even names     So by the same virtue  only FALSE is guaranteed to be exactly equal to FALSE    gt  identical F  FALSE   1  TRUE  gt  identical 0  FALSE   1  FALSE  gt  F  lt -  hello   gt  identical F  FALSE   1  FALSE   If this concerns you  always use isTRUE   or identical x  FALSE  to check for equivalence with TRUE and FALSE respectively     is not doing what you think it is

[r] What evaluates to True/False in R?

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