data(iris)
columns(iris, Sepal.Length, Sepal.Width)
columns(iris, -Species)
columns(iris, Species, "^.") # move 'Species' to the first position
columns(iris, -"^Petal") # remove columns which names start with 'Petal'
columns(iris, -5) # remove fifth column
data(mtcars)
columns(mtcars, mpg:qsec) # keep columns from 'mpg' to 'qsec'
columns(mtcars, mpg %to% qsec) # the same result
# standard and non-standard evaluation
many_vars = c("am", "vs", "cyl")
columns(mtcars, many_vars)
# character expansion
dfs = data.frame(
a = rep(10, 5),
b_1 = rep(11, 5),
b_2 = rep(12, 5),
b_3 = rep(12, 5),
b_4 = rep(14, 5),
b_5 = rep(15, 5)
)
i = 1:5
columns(dfs, b_1 %to% b_5)
columns(dfs, "b_{i}") # the same result
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