transakcje<-read.table(file = "transakcje.csv", nrows = 1000, sep=",", header= TRUE)
konta<-read.table(file = "kona.csv", nrows=100, sep=",", header = TRUE)

#liczymy srednia, dane wczytujemy do pamieci porcjami
readToChunk<-function(fileName, colname, chunkSize){
  file<-fileName
  connection<-file(description = file,open="r")
  index<-0
  counter<-0
  suma<-0
  chunk<-read.table(connection,nrows=chunkSize,header=TRUE,sep=",")
  columNames <- names(chunk)

  repeat{
    index<-index+1
    print(paste0("sum: ", suma,"counter: ",counter))
    #chunk<-na.omit(chunk)
    suma<-suma+sum(chunk[[colname]])
    counter<-counter+nrow(chunk)
    if (nrow(chunk) !=chunkSize){
      print(paste0("suma:", suma, "counter:", counter))
      break;
  }

  chunk<-read.table(connection, nrows=chunkSize, fill=TRUE,skip = 0, header=FALSE, sep=",",col.names = columNames)
}
  close.connection(connection)
  suma/counter
}

#readtoChunk("transacje.csv", "amount", 1000) w konsoli


#ZADANIE2 DO BAZY
#wczytywanie do bazy

install.packages("DBI")
install.packages("RSQLite")
library(DBI)
library(RSQLite) #ladowanie

readtoDataBase<-function(filepath,basepath,tableName, chunkSize,sepa=","){
  conwithFile<-file(description = filepath,open="r")
  dbCon <-dbConnect(SQLite(), basepath)
  dataChunk<-read.table(conwithFile,nrows = chunkSize, header = TRUE, fill = TRUE, sep=sepa)
  columnNames<-names(dataChunk)
  dbwriteTable(dbCon,tableName,dataChunk,append=TRUE,overwrite = FALSE)

   repeat{
     if (nrown(dataChunk)!=chunkSize)
       break
      dataChunk<-read.table(conwithFile,nrows=chunkSize, skip=0, header-FALSE, fill=TRUE, sep=sepa, col.names = columnNames)
      dbwriteTable(dbCon,tablename,dataChunk,append=TRUE, overwrite=FALSE)
      }
  close.connectio(conwithFile)
  dbDisconnect(dbCon)
}

#readtoDataBase("kona.csv", "baza.sqllite", "konta",100)