DSD_ReadDB: Read a Data Stream from an open DB Query

Description

A DSD class that reads a data stream from an open DB result set from a relational database with using R's data base interface (DBI).

Usage

DSD_ReadDB(
  result,
  k = NA,
  o = NA,
  class = NULL,
  outlier = NULL,
  description = NULL
)

Value

An object of class DSD_ReadDB (subclass of DSD_R, DSD).

Arguments

result: An open DBI result set.
k: Number of true clusters, if known.
o: Number of outliers, if known.
class: column index for the class/cluster assignment.
outlier: column index for the outlier mark.
description: a character string describing the data.

Author

Michael Hahsler, Dalibor Krleža

Details

This class provides a streaming interface for result sets from a data base with via DBI. You need to connect to the data base and submit a SQL query using dbGetQuery() to obtain a result set. Make sure that your query only includes the columns that should be included in the stream (including class and outlier marking columns). Do not forget to close the result set and the data base connection.

Examples

Run this code


### create a data base with a table with 3 Gaussians
library("RSQLite")
con <- dbConnect(RSQLite::SQLite(), ":memory:")

points <- get_points(DSD_Gaussians(k=3, d=2, outliers=1,
  outlier_options=list(outlier_horizon=600)), 600,
  class = TRUE, outlier = TRUE)
points <- cbind(points, outlier=attr(points,"outlier"))
head(points)

dbWriteTable(con, "gaussians", points)

### prepare a query result set
res <- dbSendQuery(con, "SELECT X1, X2, class, outlier FROM gaussians")
res

### create a stream interface to the result set
stream <- DSD_ReadDB(res, k=3, o=1, class = 3, outlier = 4)

### get points
get_points(stream, 5, class = TRUE, outlier=TRUE)
plot(stream)

### clean up
dbClearResult(res)
dbDisconnect(con)

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