These functions returns criteria functions which could be used in different
situation - see keep, except, recode, na_if,
%i%, %d%, count_if, match_row etc. For
example, gt(5) returns function which tests whether its argument
greater than five.
fixed("apple") return function which tests whether its argument
contains "apple". Logical operations (|, &, !, xor) are defined for these
functions.
List of functions:
gt greater than
ge/gte greater than or equal
eq equal
ne/neq not equal
lt less than
le/lte less than or equal
thru checks whether value is inside interval.
thru(0,1) is equivalent of x>=0 & x<=1 or ge(0) &
le(1)
%thru% infix version of thru, e. g. 0 %thru% 1
regex use POSIX 1003.2 extended regular expressions. For details see grepl
perl perl-compatible regular expressions. For details see grepl
fixed pattern is a string to be matched as is. For details see grepl
to returns function which gives TRUE for all elements of
vector before the first occurrence of x and for x.
from returns function which gives TRUE for all elements of
vector after the first occurrence of x and for x. from and
to are intended for usage with keep and except.
not_na return TRUE for all non-NA elements of vector.
other return TRUE for all elements of vector. It is intended
for usage with if_val, keep, except
items return TRUE for elements of vector with given
sequential number. It is intended for usage with keep, except
eq(x)ne(x)
neq(x)
lt(x)
gt(x)
le(x)
lte(x)
ge(x)
gte(x)
perl(pattern, ignore.case = FALSE, useBytes = FALSE)
regex(pattern, ignore.case = FALSE, useBytes = FALSE)
fixed(pattern, ignore.case = FALSE, useBytes = FALSE)
thru(lower, upper)
lower %thru% upper
from(x)
to(x)
items(...)
not_na(x)
other(x)
as.criterion(crit)
vector
character string containing a regular expression (or character
string for fixed) to be matched in the given character vector.
Coerced by as.character to a character string if possible.
logical see grepl
logical see grepl
vector/single value - lower bound of interval
vector/single value - upper bound of interval
numeric indexes of desired items
vector of values/function which returns logical or vector. It will be converted to function of class criterion.
function of class 'criterion' which tests its argument against condition and return logical value
# NOT RUN {
# operations on vector
1:6 %d% gt(4) # 1:4
1:6 %d% (1 | gt(4)) # 2:4
letters %i% (fixed("a") | fixed("z")) # a, z
letters %i% from("w") # w, x, y, z
letters %i% to("c") # a, b, c
letters %i% (from("b") & to("e")) # b, d, e
c(1, 2, NA, 3) %i% other # c(1, 2, 3)
# examples with count_if
df1 = data.frame(
a=c("apples", "oranges", "peaches", "apples"),
b = c(32, 54, 75, 86)
)
count_if(gt(55), df1$b) # greater than 55 = 2
count_if(ne(75), df1$b) # not equal 75 = 3
count_if(ge(32), df1$b) # greater than or equal 32 = 4
count_if(gt(32) & lt(86), df1$b) # greater than 32 and less than 86 = 2
# via different kinds of 'thru'
count_if(thru(35, 80), df1$b) # greater than or equals to 35 and less than or equals to 80 = 2
# infix version
count_if(35 %thru% 80, df1$b) # greater than or equals to 35 and less than or equals to 80 = 2
# values that started on 'a'
count_if(regex("^a"), df1) # 2
# count_row_if
count_row_if(regex("^a"), df1) # c(1,0,0,1)
# examples with 'keep' and 'except'
data(iris)
iris %keep% to("Petal.Width") # column 'Species' will be removed
# 'Sepal.Length', 'Sepal.Width' will be left
iris %except% from("Petal.Length")
# except first column
iris %except% items(1)
# if_val examples
# From SPSS: RECODE QVAR(1 THRU 5=1)(6 THRU 10=2)(11 THRU HI=3)(ELSE=0).
set.seed(123)
qvar = sample((-5):20, 50, replace = TRUE)
recode(qvar, 1 %thru% 5 ~ 1, 6 %thru% 10 ~ 2, 11 %thru% hi ~ 3, other ~ 0)
# the same result
recode(qvar, 1 %thru% 5 ~ 1, 6 %thru% 10 ~ 2, ge(11) ~ 3, other ~ 0)
# }
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