Logical Coding
Usage
logique(a)
Arguments
a
|
real-valued vector, with no missing values.
|
Description
Simple logical coding of a vector: each value in the
vector is replaced by a 1 (if it is above or equal to the median),
by a 0 (if it is below the median).Value
matrix of length(a)
rows, and two columns. The first column contains the
logically coded values of a
, and the second column contains their
complements. Hence each row of this returned matrix necessarily sums to 1.BACKGROUND
This form of coding is suitable for a subsequent correspondence analysis.
When all variable have been logically (or fuzzily) coded, the row masses
(proportional to the row sums) are identical. Logical coding results in
the input being in complete disjunctive form.References
J.-P. Benzecri
Correspondence Analysis Handbook
Marcel Dekker, Basel, 1992.See Also
flou
, ca
, supplr
, supplc
.Examples
# Logical coding of input variables, `a', `b', `c':
a.log <- logique(a)
b.log <- logique(b)
c.log <- logique(c)
newdata <- cbind(a.log, b.log, c.log)
ca.newdata <- ca(newdata)