rsummary: Compute usable summary of columns of remote table.

In rquery: Relational Query Generator for Data Manipulation at Scale

Compute usable summary of columns of remote table.

Description

Compute per-column summaries and return as a data.frame. Warning: can be an expensive operation.

Usage

rsummary(
  db,
  tableName,
  ...,
  countUniqueNum = FALSE,
  quartiles = FALSE,
  cols = NULL,
  qualifiers = NULL
)

Arguments

db	database connection.
tableName	name of table.
...	force additional arguments to be bound by name.
countUniqueNum	logical, if TRUE include unique non-NA counts for numeric cols.
quartiles	logical, if TRUE add Q1 (25%), median (50%), Q3 (75%) quartiles.
cols	if not NULL set of columns to restrict to.
qualifiers	optional named ordered vector of strings carrying additional db hierarchy terms, such as schema.

Details

For numeric columns includes NaN in nna count (as is typical for R, e.g., is.na(NaN)).

Value

data.frame summary of columns.

Examples

if (requireNamespace("DBI", quietly = TRUE) &&
  requireNamespace("RSQLite", quietly = TRUE)) {
  d <- data.frame(p= c(TRUE, FALSE, NA),
                  s= NA,
                  w= 1:3,
                  x= c(NA,2,3),
                  y= factor(c(3,5,NA)),
                  z= c('a',NA,'a'),
                  stringsAsFactors=FALSE)
  db <- DBI::dbConnect(RSQLite::SQLite(), ":memory:")
  RSQLite::initExtension(db)
  rq_copy_to(db, "dRemote", d,
              overwrite = TRUE, temporary = TRUE)
  print(rsummary(db, "dRemote"))
  DBI::dbDisconnect(db)
}

rquery documentation built on Aug. 20, 2023, 9:06 a.m.