type-cast: Cast columns of 'db.obj' objects to other types

In greenplum-db/GreenplumR: A Fast, Easy-to-Use Tool for Manipulating Tables in Databases

Cast columns of db.obj objects to other types

Description

Coerce db.obj object columns into other types. col.types displays the types of each column. as.Date converts to date (no time of day); as.time converts to time of day (no date); as.timestamp converts to both date and time; as.interval converts to time interval. db.date.style can display or set the date style for a particular connection.

Usage

## S4 method for signature 'db.obj'
as.integer(x, ...)

## S4 method for signature 'db.obj'
as.character(x, array = TRUE, ...)

## S4 method for signature 'db.obj'
as.double(x, ...)

## S4 method for signature 'db.obj'
as.logical(x, ...)

## S4 method for signature 'db.obj'
as.numeric(x, ...)

## S4 method for signature 'db.obj'
as.Date(x, ...)

db.date.style(conn.id = 1, set = NULL)

as.time(x, ...)

as.timestamp(x, ...)

as.interval(x, ...)

col.types(x)

Arguments

x	A db.obj object. All columns of the object will be converted into the target type. If the column contains arrays, the array will be converted into an array of the target type.
array	A logical, default is TRUE. If array is TRUE, then an array column is converted into an array of strings. If array is FALSE, then an array column is converted into a string column, i.e. array[1,2,3] is casted into '\{1,2,3\}'.
...	further arguments passed to or from other methods This is currently not implemented.
conn.id	An integer, default is 1. The connection ID for the database connection.
set	A string, default is NULL. It can be "us" or "european". If it is NULL, db.date.style displays the current date style in the connected database. Otherwise, it sets the date style for the connected database.

Value

A db.Rquery object, which is a SQL query which combine all columns into an array.

col.types returns a vector of characters, which are the column types of x.

Author(s)

Author: Predictive Analytics Team at Pivotal Inc.

Maintainer: Frank McQuillan, Pivotal Inc. [e-mail]

See Also

by,db.obj-method is usually used together with aggregate functions.

Examples

## Not run: 


## set up the database connection
## Assume that .port is port number and .dbname is the database name
cid <- db.connect(port = .port, dbname = .dbname, verbose = FALSE)

x <- as.db.data.frame(abalone, conn.id = cid, verbose = FALSE)
lk(x, 10)

z <- as.integer(x > 1)
lookat(z, 10)

z <- as.integer(x[,2] == "M")
lookat(z, 10)

col.types(x)

col.types(z)

db.disconnect(cid, verbose = FALSE)

## End(Not run)

greenplum-db/GreenplumR documentation built on Sept. 2, 2023, 8:09 a.m.