sbrac {labelr}

Safely Extract Elements of a Labeled Data Frame

Description

sbrac allows one to do "bracket-like" row and/or column selection (without actual brackets) on a labelr-labeled data.frame in a manner that preserves its labelr label attributes.

Usage

sbrac(data, ri = NULL, ci = NULL, partial = FALSE)

Arguments

data

the data.frame from which columns will be selected.

ri

row indices (integer positional or logical) or row.names (or partial row.names if partial = TRUE) to be selected.

ci

column indices (integer positional or logical) or column / variable names (or partial column names if partial = TRUE) to be selected.

partial

if TRUE, any row or column that contains the relevant character substring will be selected (e.g., sbrac(mtcars, c("Maz"), c("di")) will return all "Mazda" car rows and the column "disp").

Details

sbrac allows one to select rows and columns of a data.frame in a bracket- like fashion, using integers (positional indices), logicals, or (partial) character names (row names and column/variable names). Whereas some forms of Base R bracket subsetting will discard (destroy) labelr attributes, sbrac preserves them. For example, sbrac(df, 1:5, 2:4) returns a data.frame (with any labelr attribute meta-data intact), consisting of rows 1-5 and columns 2-4 of data.frame df; while sbrac(mtcars, "Maz", "a", partial = TRUE) returns all variables with substring "a" in their names for all rows with substring "Maz" in their row names. Integer indices (only) can be enclosed in -c() for negative index selection (i.e., "select not these"), (where sbrac(df, -c(1,2), "x", partial = TRUE) means select all rows of df other than rows 1 and 2 and all columns that feature the letter "x" in their names. See also ssubset, sfilter, sselect, sdrop, ssort, and srename, as well as slab and flab for other labelr attribute-preserving subsetting tools.

Value

a labelr label attribute-preserving data.frame, consisting of the selected rows and/or columns index-selected.

Examples

# create a copy of the mtcars data set
mtc2 <- mtcars

# variable names and their labels
names_labs_vec <- c(
  "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 (0 = V-shaped, 1 = straight)",
  "am" = "Transmission (0 = automatic, 1 = manual)",
  "gear" = "Number of forward gears",
  "carb" = "Number of carburetors"
)

# assign variable labels
mtc2 <- add_name_labs(mtc2,
  vars = names(names_labs_vec),
  labs = names_labs_vec
)

# examples of sbrac() functionality
sbrac(mtc2, 1:4, ) # commas used in a bracket-like way: row 1:4 and all cols
sbrac(mtc2, , 1:4) # commas used in a bracket-like way: all rows and cols 1:4
sbrac(mtc2, 1, 2) # 1 is row, 2 is col
sbrac(mtc2, -c(8:32), -c(1:8)) # select NOT-these rows and cols (-)
sbrac(mtc2, 1:5, 1:2) # rows 1-5, cols 1 and 2

# if partial = TRUE, partial matching to get all Mazda or Merc + all
# ...vars with "ar" in name
sbrac(mtc2, c("Mazda", "Merc"), c("ar"), partial = TRUE) # see what this does
mtc3 <- sbrac(mtc2, c("45"), 1:2, partial = TRUE) # see what this does
get_labs_att(mtc3, "name.labs") # name.labs still there