ox_xtract_group: Data for a group of items, as a tidy dataframe
In acobos/ox: Reads OpenClinica xml export files

Description Usage Arguments Value Examples

Returns a tidy dataframe from a ox_all object, containing data for all items of the specified group. In the resulting dataframe, each item is a variable, and each row is an observation; dataframe variables are identified by their item_oid (or optionally, by their item_name), and are one of the following classes: Date, numeric, or character. Optionally, items with codelists can be defined as factor.

1 2	ox_xtract_group(ox_obj, group, define_factors = FALSE, use_item_names = FALSE)

`ox_obj`	An object of class `ox_all`, as returned by `ox::ox_all()`.
`group`	A group of items, as `character` value. Must be one of the `group_oid` values in `ox_obj$metadata$group_def`.
`define_factors`	A `logical` value. When `TRUE`, items with codelists are defined as factors using the codelist. Defaults to `FALSE`.
`use_item_names`	A `logical` value. When `TRUE`, `item_name` in `ox_obj$metadata$item_def` are used as variable names in the resulting dataframe. Othewise, `item_oid` are used. Defaults to `FALSE`.

A dataframe with study, subject, event, form, group and group repeat keys, plus all items in group as variables.

# The example odm1.3 xml file address
my_file <- system.file("extdata",
                       "odm1.3_full_example.xml",
                       package = "ox",
                       mustWork = TRUE)

# Parsing the xml file
library(XML)
doc <- xmlParse(my_file)

# Create ox_all object
my_study <- ox_all(doc)

# Item groups
unique(my_study$metadata$group_def$group_oid)

# Extract data for a group
demo <- ox_xtract_group(my_study,
                        group = "IG_DEMO_DEMOGRAPHICDATA")
head(demo)

# Same, using item names to identify vars, and
# defining factors for items with codelist
demo_2 <- ox_xtract_group(my_study,
                          group = "IG_DEMO_DEMOGRAPHICDATA",
                          define_factors = TRUE,
                          use_item_names = TRUE)
head(demo_2)