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← SASnRApply attributes to variables

Introduction

Apply attributes to variables

SAS (Base SAS)+

R (tidyverse)+

#==============================================================================
# Create the dataset
#==============================================================================

library(tidyverse)

adsl01 <- tribble(
  ~usubjid, ~sex, ~age, ~trt01pn,
  "101",    "M",   25,    1,
  "102",    "F",   30,    2,
  "103",    "M",   27,    1
)

 

#==============================================================================
# Assign labels and lengths using attr()
#==============================================================================

attr(adsl01$usubjid, "label") <- "Unique Subject Identifier"
attr(adsl01$usubjid, "length") <- 10

attr(adsl01$sex, "label") <- "Sex"
attr(adsl01$sex, "length") <- 1

attr(adsl01$age, "label") <- "Age"
attr(adsl01$age, "length") <- 8

attr(adsl01$trt01pn, "label") <- "Planned Treatment for Period 01 (N)"
attr(adsl01$trt01pn, "length") <- 8

 

#==============================================================================
# View all labels and lengths
#==============================================================================

# Create a tibble with variable names and their labels
label_table <- tibble(
  variable = names(adsl01),
  label = map_chr(adsl01, ~ attr(.x, "label")),
  length = map_int(adsl01, ~ attr(.x, "length"))
)

We use tribble() to define the dataset adsl01 with four variables.
Using attr(..., "label") , we assign descriptive labels to each variable.
Using attr(..., "length") , we assign length attribute to each variable.
R doesn't enforce character length truncation — the "length" attribute is just metadata.
Length attribute is just to show for documentation, or SAS-like simulation.