Brackets {admisc} | R Documentation |
Functions to extract information from an expression written in SOP - sum of products form, (or from the canonical DNF - disjunctive normal form) for multi-value causal conditions. It extracts either the values within brackets, or the causal conditions' names outside the brackets.
insideBrackets(x, type = "{", invert = FALSE) outsideBrackets(x, type = "{") curlyBrackets(x, outside = FALSE) roundBrackets(x, outside = FALSE)
x |
Character, a DNF/SOP expression. |
type |
Brackets type: curly, round or square |
invert |
Logical, if activated returns whatever is not within the brackets |
outside |
Logical, if activated returns the conditions' names outside the brackets |
Expressions written in SOP - sum of products are used in Boolean logic, signaling a disjunction of conjunctions.
These expressions are useful in Qualitative Comparative Analysis, a social science methodology that is employed in the context of searching for causal configurations that are associated with a certain outcome.
They are also used to draw Venn diagrams with the package venn
, which draws any
kind of set intersection (conjunction) based on a custom SOP expression.
The functions curlyBrackets
and roundBrackets
are just special
cases of the functions insideBrackets
and outsideBrackets
, using
the argument type
as either "{"
or "("
.
The function outsideBrackets
itself can be considered a special case of the
function insideBrackets
, when it uses the argument invert = TRUE
.
Adrian Dusa
dnf <- "A{1} + B{2}C{0}" insideBrackets(dnf) # 1, 2, 0 insideBrackets(dnf, invert = TRUE) # A, B, C curlyBrackets(dnf) # 1, 2, 0 curlyBrackets(dnf, outside = TRUE) # A, B, C