View source: R/parseRangeCode.R
parseRangeCode | R Documentation |
parseRangeCode: Converts inequalities of up to two comparators stored in a vector of strings into an executable R expression. For instance, parseRangeCode(c("1 < Y < 20", "40 < Y")) will yield the expression (1<Y)&(Y<20)&(40<Y). parseRCode: simply parse an R string into an expression.
parseRangeCode(code)
code |
(Required) For parseRangeCode: A vector of strings that contain
inequalities along with various seperators (see below). Each inequality
should have either 1 or 2 comparators. For parseRCode: a code string. For
|
The parseRangeCode
function converts various kinds of
ranges/inequalities that are normally not handled by R into R-executable
expressions. For instance it will convert inequalities of the form "A < B <
C" into (A < B) & (B < C), where < may be replaced with any comparator.
Moreover it allows inqualities to be concatenated by the symbols "&", ";" or
"," which are all treated as equivalent to the logical "and" (i.e. "&").
Thus "A < B <C & D > E, F <= G" will be converted into (A < B)&(B < C)&(D >
E)&(F <= G). In addition if code
is a vector with more than one
element, each element will be parsed and then concatenated into a single
expression with "&". Hence c("1 < Y", "2 < Z <= 5") would become (1 <
Y)&(2 < Z)&(Z <= 5)
.
An expression constructed as detailed above.
The character "|" is not allowed in any of the expressions
contained in "code" for the parseRangeCode
function.
Romain Francois
subset
, parse
# Examples of using subsets
## Not run:
exData <- data.frame( Y = rnorm(200), B = rnorm( 200 ) )
subs1 <- parseRangeCode("1 < Y < 10 & 1 > B > -2")
exData[ eval(subs1, exData), ]
subs2 <- parseRangeCode(c("1 < Y < 10", "1 > B > -2"))
exData[ eval(subs1, exData), ]
expr <- parseRCode("rnorm(30)")
eval( expr )
## End(Not run)
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