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Extract the subset of data based on result metadata

Source: R/meta_utils.R
get_meta_subset.Rd

Given a row_id value and a result column, this function will return the subset of data referenced by the tplyr_meta object associated with that 'cell', which provides traceability to tie a result to its source.

Usage

get_meta_subset(x, row_id, column, add_cols = vars(USUBJID), ...)

# S3 method for data.frame
get_meta_subset(
  x,
  row_id,
  column,
  add_cols = vars(USUBJID),
  target = NULL,
  pop_data = NULL,
  ...
)

# S3 method for tplyr_table
get_meta_subset(x, row_id, column, add_cols = vars(USUBJID), ...)

Arguments

x

A built Tplyr table or a dataframe

row_id

The row_id value of the desired cell, provided as a character string

column

The result column of interest, provided as a character string

add_cols

Additional columns to include in subset data.frame output

...

additional arguments

target

A data frame to be subset (if not pulled from a Tplyr table)

pop_data

A data frame to be subset through an anti-join (if not pulled from a Tplyr table)

Value

A data.frame

Details

If a Tplyr table is built with the metadata=TRUE option specified, then metadata is assembled behind the scenes to provide traceability on each result cell derived. The functions get_meta_result() and get_meta_subset() allow you to access that metadata by using an ID provided in the row_id column and the column name of the result you'd like to access. The purpose is of the row_id variable instead of a simple row index is to provide a sort resistant reference of the originating column, so the output Tplyr table can be sorted in any order but the metadata are still easily accessible.

The tplyr_meta object provided a list with two elements - names and filters. The metadata contain every column from the target data.frame of the Tplyr table that factored into the specified result cell, and the filters contains all the necessary filters to subset to data summarized to create the specified result cell. get_meta_subset() additionally provides a parameter to specify any additional columns you would like to include in the returned subset data frame.

Examples

t <- tplyr_table(mtcars, cyl) %>%
  add_layer(
    group_desc(hp)
  )


dat <- t %>% build(metadata = TRUE)

get_meta_subset(t, 'd1_1', 'var1_4', add_cols = dplyr::vars(carb))
#>                carb cyl  hp
#> Datsun 710        1   4  93
#> Merc 240D         2   4  62
#> Merc 230          2   4  95
#> Fiat 128          1   4  66
#> Honda Civic       2   4  52
#> Toyota Corolla    1   4  65
#> Toyota Corona     1   4  97
#> Fiat X1-9         1   4  66
#> Porsche 914-2     2   4  91
#> Lotus Europa      2   4 113
#> Volvo 142E        2   4 109

m <- t$metadata
dat <- t$target

get_meta_subset(t, 'd1_1', 'var1_4', add_cols = dplyr::vars(carb), target = target)
#>                carb cyl  hp
#> Datsun 710        1   4  93
#> Merc 240D         2   4  62
#> Merc 230          2   4  95
#> Fiat 128          1   4  66
#> Honda Civic       2   4  52
#> Toyota Corolla    1   4  65
#> Toyota Corona     1   4  97
#> Fiat X1-9         1   4  66
#> Porsche 914-2     2   4  91
#> Lotus Europa      2   4 113
#> Volvo 142E        2   4 109