I have a data frame with labeled columns meaning I have both column names and one label for each column. The following code creates an analogous data frame:
data(mtcars)
mtcars = apply_labels(mtcars,
mpg = "Miles/(US) gallon",
cyl = "Number of cylinders",
disc = "Displacement (cu. in.)",
hp = "Gross horsepower",
drat = "Rear axle ratio",
wt = "weight (1000 lbs)",
qsec = "1/4 mile time",
vs = "Engine",
am = "Transmission"
gear = "Number of forward gears"
carb = "Number of carburetors"
My goal is to select columns by their labels ("Miles/(US) gallon", etc.). Does anyone know how to get access to those or know a function returning those labels?
Thank you very much for your help.
I assume you are using the expss package to apply the labels. This package also contains the function var_lab which returns the label of any column. You can get a vector of labels using sapply(mtcars, var_lab). Then you can use this vector to subset the columns you need from the data frame.
library(expss)
data(mtcars)
mtcars = apply_labels(mtcars,
mpg = "Miles/(US) gallon",
cyl = "Number of cylinders",
disp = "Displacement (cu. in.)",
hp = "Gross horsepower",
drat = "Rear axle ratio",
wt = "weight (1000 lbs)",
qsec = "1/4 mile time",
vs = "Engine",
am = "Transmission",
gear = "Number of forward gears",
carb = "Number of carburetors")
labs <- sapply(mtcars,var_lab)
print(labs)
## mpg cyl disp
## "Miles/(US) gallon" "Number of cylinders" "Displacement (cu. in.)"
## hp drat wt
## "Gross horsepower" "Rear axle ratio" "weight (1000 lbs)"
## qsec vs am
## "1/4 mile time" "Engine" "Transmission"
## gear carb
## "Number of forward gears" "Number of carburetors"
subset <- mtcars[,labs %in% c('Number of cylinders','Gross horsepower')]
head(subset)
## cyl hp
## Mazda RX4 6 110
## Mazda RX4 Wag 6 110
## Datsun 710 4 93
## Hornet 4 Drive 6 110
## Hornet Sportabout 8 175
## Valiant 6 105