Logical vector with multiple columns in R

Question

I have te following dataframe:

a    b     c     d     e
TRUE TRUE FALSE  TRUE  TRUE
FALSE TRUE  TRUE  TRUE FALSE
TRUE TRUE FALSE  TRUE  TRUE
TRUE TRUE  TRUE FALSE  TRUE
TRUE TRUE  TRUE  TRUE  TRUE
TRUE TRUE  TRUE  TRUE  TRUE

I would like to create an extra column , say f, with the following logic:

TRUE = If all the columns in the corresponding row are all TRUE or all FALSE.
FALSE = if one or more colums differ from the other columns in the corresponding row.

In this example the output would be

a    b     c     d     e     f
TRUE TRUE FALSE  TRUE  TRUE  FALSE
FALSE TRUE  TRUE  TRUE FALSE  FALSE
TRUE TRUE FALSE  TRUE  TRUE  FALSE
TRUE TRUE  TRUE FALSE  TRUE  FALSE
TRUE TRUE  TRUE  TRUE  TRUE  TRUE
TRUE TRUE  TRUE  TRUE  TRUE  TRUE

Answer 1

Use this:

DF$f <- apply(DF, 1, function(x)(all(x) || all(!x)))

where "DF" is your dataframe.

Answer 2

Alternatively, exploiting the fact that logical values are just 0s and 1s for arithmetic:

rowMeans(dat) %in% 0:1
[1] FALSE FALSE FALSE FALSE  TRUE  TRUE