Erik,
Can you store the data as a blob? For example:
> #create string, compress with gzip, convert to SQLite blob string
> string <- "gzip this string, store as blob in SQLite database"
> string.gz <- memCompress(string, type="gzip")
> string.sqlite <-
paste("x'",paste(string.gz,collapse=""),"'",sep="")
> #create database and table with a BLOB column
> library(RSQLite)
Loading required package: DBI> con <- dbConnect(dbDriver("SQLite"),
"compress.sqlite")
> dbGetQuery(con, "CREATE TABLE Compress (id INTEGER, data BLOB);")
NULL
> #insert the string as a blob
> query <- paste("INSERT INTO Compress (id, data) VALUES (1, ",
+ string.sqlite, ");", sep="")> dbGetQuery(con, query)
NULL
> #recover the blob, decompress, and convert back to a string
> result <- dbGetQuery(con, "SELECT data FROM Compress;")
> string.gz <- result[[1]][[1]]
> string <- memDecompress(string.gz, type="gzip")
> rawToChar(string)
[1] "gzip this string, store as blob in SQLite database"
-Matt
On Fri, 2010-07-09 at 12:51 -0400, Erik Wright wrote:> Hello,
>
> I would like to compress a long string (character vector), store the
compressed string in the text field of a SQLite database (using RSQLite), and
then load the text back into memory and decompress it back into the the original
string. My character vector can be compressed considerably using standard
gzip/bzip2 compression. In theory it should be much faster for me to
compress/decompress a long string than to write the whole string to the hard
drive and then read it back (not to mention the saved hard drive space).
>
> I have tried accomplishing this task using memCompress() and
memDecompress() without success. It seems memCompress can only convert a
character vector to raw type which cannot be treated as a string. Does anyone
have ideas on how I can go about doing this, especially using the standard base
packages?
>
> Thanks!,
> Erik
>
>
> > sessionInfo()
> R version 2.11.0 (2010-04-22)
> x86_64-apple-darwin9.8.0
>
> locale:
> [1] en_US.UTF-8/en_US.UTF-8/C/C/en_US.UTF-8/en_US.UTF-8
>
> attached base packages:
> [1] stats graphics grDevices utils datasets methods base
>
> loaded via a namespace (and not attached):
> [1] tools_2.11.0
>
> ______________________________________________
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> PLEASE do read the posting guide
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> and provide commented, minimal, self-contained, reproducible code.
--
Matthew S. Shotwell
Graduate Student
Division of Biostatistics and Epidemiology
Medical University of South Carolina
http://biostatmatt.com