Keep or drop elements by name/criteria in data.frame/matrix
keep selects variables/elements from data.frame by their names or by
criteria (see criteria). except drops variables/elements from
data.frame by their names or by criteria. Names at the top-level can be
unquoted (non-standard evaluation). For standard evaluation of parameters you
can surround them by round brackets. See examples. Methods for list will apply
keep/except to each element of the list separately.
.keep/.except are versions which works with
default_dataset.
keep(data, ...) .keep(...) except(data, ...) .except(...)
data |
data.frame/matrix/list |
... |
column names of type character/numeric or criteria/logical functions |
object of the same type as data
data(iris)
keep(iris, Sepal.Length, Sepal.Width)
except(iris, Species)
keep(iris, Species, other()) # move 'Species' to the first position
keep(iris, to("Petal.Width")) # keep all columns up to 'Species'
except(iris, perl("^Petal")) # remove columns which names start with 'Petal'
except(iris, 5) # remove fifth column
data(mtcars)
keep(mtcars, from("mpg") & to("qsec")) # keep columns from 'mpg' to 'qsec'
keep(mtcars, mpg %to% qsec) # the same result
# standard and non-standard evaluation
many_vars = c("am", "vs", "cyl")
## Not run:
keep(mtcars, many_vars) # error - names not found: 'many_vars'
## End(Not run)
keep(mtcars, (many_vars)) # ok
# character expansion
dfs = data.frame(
a = 10 %r% 5,
b_1 = 11 %r% 5,
b_2 = 12 %r% 5,
b_3 = 12 %r% 5,
b_4 = 14 %r% 5,
b_5 = 15 %r% 5
)
i = 1:5
keep(dfs, b_1 %to% b_5)
keep(dfs, text_expand("b_{i}")) # the same resultPlease choose more modern alternatives, such as Google Chrome or Mozilla Firefox.