Home - News ( United States | United Kingdom | Italy | Germany ) - Football scores

Showing content from https://winvector.github.io/rquery/reference/project.html below:

project data by grouping, and adding aggregate columns. — project • rquery

Supports bquote() .()-style name abstraction including .(-) notation to promote strings to names (please see here: https://github.com/WinVector/rquery/blob/master/Examples/Substitution/Substitution.md).

project(source, ..., groupby = c(), env = parent.frame())

project_nse(source, ..., groupby = c(), env = parent.frame())

aggregate_nse(source, ..., groupby = c(), env = parent.frame())

source to select from.

new column assignment expressions.

grouping columns.

environment to look for values in.

project node.

if (requireNamespace("DBI"
, quietly 
= TRUE) && requireNamespace("RSQLite"
, quietly 
= TRUE)) {
  my_db <- DBI::dbConnect(RSQLite::SQLite()
, 
":memory:")
  d <- rq_copy_to(
    my_db
, 
'd'
, 
data.frame(
group 
= c('a'
, 
'a'
, 
'b'
, 
'b')
, val 
= 1:4
, stringsAsFactors 
= FALSE))

  op_tree <- d %.>%
    project(.
, groupby 
= "group"
, 
vmax %:=% max(val))
  cat(format(op_tree))
  sql <- to_sql(op_tree
, 
my_db)
  cat(sql)
  execute(my_db
, 
op_tree) %.>%
     print(.)

  op_tree <- d %.>%
    project(.
, groupby 
= NULL
, 
vmax %:=% max(val))
  cat(format(op_tree))
  sql <- to_sql(op_tree
, 
my_db)
  cat(sql)
  execute(my_db
, 
op_tree) %.>%
    print(.)

  DBI::dbDisconnect(my_db)
}
#> mk_td("d", c(
#>   "group",
#>   "val")) %.>%
#>  project(., vmax := max(val),
#>   groupby = c('group'))
#> SELECT `group`, max ( `val` ) AS `vmax` FROM (
#>  SELECT
#>   `group`,
#>   `val`
#>  FROM
#>   `d`
#>  ) tsql_86188167191619545564_0000000000
#> GROUP BY
#>  `group`
#>   group vmax
#> 1     a    2
#> 2     b    4
#> mk_td("d", c(
#>   "group",
#>   "val")) %.>%
#>  project(., vmax := max(val),
#>   groupby = c())
#> SELECT max ( `val` ) AS `vmax` FROM (
#>  SELECT
#>   `val`
#>  FROM
#>   `d`
#>  ) tsql_06969961980534496516_0000000000
#>   vmax
#> 1    4

RetroSearch is an open source project built by @garambo | Open a GitHub Issue

Search and Browse the WWW like it's 1997 | Search results from DuckDuckGo

HTML: 3.2 | Encoding: UTF-8 | Version: 0.7.4