#' @demoTitle baseball-sample
#'
#' Demo sampling data from Aster tables
#'
#' To install and use baseball demo dataset in Aster:
#'
#' 1. download baseball.zip from
#' https://bitbucket.org/grigory/toaster/downloads/baseball.zip
#' 2. run script to create data set in Aster
#' sh load_baseball_data.sh -d mydbname -U username -w mypassword
#' 3. create Aster ODBC DSN on your desktop
#' see https://bitbucket.org/grigory/toaster/wiki/Home#markdown-header-odbc-driver-and-dns
library(toaster)
## utility input function
readlineDef <- function(prompt, default) {
if (!is.null(prompt))
prompt = paste0(prompt, "[", default, "]: ")
else
prompt = paste0(prompt, ": ")
result = readline(prompt)
if (result == "")
return (default)
else
return (result)
}
## utility connection function
connectWithDSNToAster <- function(dsn=NULL) {
dsn = readlineDef("Enter Aster ODBC DSN: ", dsn)
tryCatch(close(conn), error=function(err) {NULL})
conn = tryCatch({
conn = odbcConnect(dsn)
odbcGetInfo(conn)
return (conn)
}, error=function(err) {
stop(paste("Can't connect to Aster - check DSN '", dsn, "'"))
})
}
## utility pause function
pause <- function() {
cat("Press ENTER/RETURN/NEWLINE to continue.")
readLines(n=1)
invisible()
}
## connect to Aster first
conn = connectWithDSNToAster()
## must be connected to baseball dataset
if(!all(isTable(conn, c('pitching', 'batting')))) {
stop("Must connect to baseball dataset and tables must exist.")
}
# Sample 1% from batting table
batters = computeSample(conn, "batting", sampleFraction=0.01)
dim(batters)
head(batters)
pause()
# Sample 1K of pitching rows for AL only
pitchers = computeSample(conn, "pitching", sampleSize=1000, where="lgid='AL'")
dim(pitchers)
tail(pitchers)
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