Map data records from block records to row records.

Map data records from block records (which each record may be more than one row) to row records (where each record is a single row).

blocks_to_rowrecs(
  tallTable,
  keyColumns,
  controlTable,
  ...,
  columnsToCopy = NULL,
  checkNames = TRUE,
  checkKeys = TRUE,
  strict = FALSE,
  controlTableKeys = colnames(controlTable)[[1]],
  tmp_name_source = wrapr::mk_tmp_name_source("bltrr"),
  temporary = TRUE,
  allow_rqdatatable = FALSE
)

# S3 method for default
blocks_to_rowrecs(
  tallTable,
  keyColumns,
  controlTable,
  ...,
  columnsToCopy = NULL,
  checkNames = TRUE,
  checkKeys = FALSE,
  strict = FALSE,
  controlTableKeys = colnames(controlTable)[[1]],
  tmp_name_source = wrapr::mk_tmp_name_source("btrd"),
  temporary = TRUE,
  allow_rqdatatable = FALSE
)

# S3 method for relop
blocks_to_rowrecs(
  tallTable,
  keyColumns,
  controlTable,
  ...,
  columnsToCopy = NULL,
  checkNames = TRUE,
  checkKeys = FALSE,
  strict = FALSE,
  controlTableKeys = colnames(controlTable)[[1]],
  tmp_name_source = wrapr::mk_tmp_name_source("bltrr"),
  temporary = TRUE,
  allow_rqdatatable = FALSE
)

Arguments

tallTable	data.frame containing data to be mapped (in-memory data.frame).
keyColumns	character vector of column defining row groups
controlTable	table specifying mapping (local data frame)
...	force later arguments to be by name.
columnsToCopy	character, extra columns to copy.
checkNames	logical, if TRUE check names.
checkKeys	logical, if TRUE check keyColumns uniquely identify blocks (required).
strict	logical, if TRUE check control table name forms
controlTableKeys	character, which column names of the control table are considered to be keys.
tmp_name_source	a tempNameGenerator from cdata::mk_tmp_name_source()
temporary	logical, if TRUE use temporary tables
allow_rqdatatable	logical, if TRUE allow rqdatatable shortcutting on simple conversions.

Value

wide table built by mapping key-grouped tallTable rows to one row per group

Details

The controlTable defines the names of each data element in the two notations: the notation of the tall table (which is row oriented) and the notation of the wide table (which is column oriented). controlTable[ , 1] (the group label) cross colnames(controlTable) (the column labels) are names of data cells in the long form. controlTable[ , 2:ncol(controlTable)] (column labels) are names of data cells in the wide form. To get behavior similar to tidyr::gather/spread one builds the control table by running an appropriate query over the data.

Some discussion and examples can be found here: https://winvector.github.io/FluidData/FluidData.html and here https://github.com/WinVector/cdata.

See also

build_pivot_control, rowrecs_to_blocks

Examples

  # pivot example
  d <- data.frame(meas = c('AUC', 'R2'),
                  val = c(0.6, 0.2))

  cT <- build_pivot_control(d,
                            columnToTakeKeysFrom= 'meas',
                            columnToTakeValuesFrom= 'val')
  blocks_to_rowrecs(d,
                    keyColumns = NULL,
                    controlTable = cT)
#>   AUC  R2
#> 1 0.6 0.2


d <- data.frame(meas = c('AUC', 'R2'),
                val = c(0.6, 0.2))
cT <- build_pivot_control(
  d,
  columnToTakeKeysFrom= 'meas',
  columnToTakeValuesFrom= 'val')

ops <- rquery::local_td(d) %.>%
  blocks_to_rowrecs(.,
                    keyColumns = NULL,
                    controlTable = cT)
cat(format(ops))
#> mk_td("d", c(
#>   "meas",
#>   "val")) %.>%
#>  non_sql_node(., CREATE TEMPORARY TABLE "OUT" AS  SELECT MAX( CASE WHEN CAST(a."meas" AS VARCHAR) = 'AUC' THEN a."val" ELSE NULL END ) "AUC", MAX( CASE WHEN CAST(a."meas" AS VARCHAR) = 'R2' THEN a."val" ELSE NULL END ) "R2" FROM "IN" a )

if(requireNamespace("rqdatatable", quietly = TRUE)) {
  library("rqdatatable")
  d %.>%
    ops %.>%
    print(.)
}
#> Loading required package: rquery
#>   AUC  R2
#> 1 0.6 0.2

if(requireNamespace("RSQLite", quietly = TRUE)) {
  db <- DBI::dbConnect(RSQLite::SQLite(), ":memory:")
  DBI::dbWriteTable(db,
                    'd',
                    d,
                    overwrite = TRUE,
                    temporary = TRUE)
  db %.>%
    ops %.>%
    print(.)
  DBI::dbDisconnect(db)
}
#>   AUC  R2
#> 1 0.6 0.2