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
Methods.
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

Package base version 6.1.5-18
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