Ops.factor
Operations for Factors and Ordered Factors
Description
Defines arithmetic, comparison, and logical operators on factors.
Usage
e1 OP e2
OP e1
Arguments
| e1, e2 |
objects, at least one of which inherits from class
"factor", for Ops.factor, or from
"ordered" for Ops.ordered.
|
Details
Each argument of the relevant class is converted to a vector,
and the relevant comparison applied to the result.
- For factors, only equality/inequality comparisons
are meaningful (the levels of a factor are unordered).
- For ordered factors, all comparisons are meaningful, and are
applied to the levels attribute, using its implied ordering.
This is a group method for the functions of the
Ops group generic,
the basic operators for arithmetic, comparison, and logic.
It succeeds only for comparison operators. The method fails for
arithmetic or logical operators.
Value
returns a logical vector for the comparison operators.
See Also
Examples
x <- 1:10
y <- factor(c("top", "bottom", "middle", "top", "bottom",
"middle", "top", "middle", "top", "bottom"))
x == y
x > y # Warning: '>' is not meaningful for factors
y1 <- ordered(c("top", "bottom", "middle", "top", "bottom",
"middle", "top", "middle", "top", "bottom"))
y2 <- ordered(c("top", "bottom", "top", "bottom", "middle", "top",
"middle", "top", "bottom", "middle" ))
y1 >= y2
# TRUE TRUE FALSE TRUE FALSE FALSE TRUE FALSE TRUE FALSE
y1 + y2 # Warning: '+' is not meaningful for ordered factors
!y1 # Warning: '!' is not meaningful for ordered factors