Hi Jia, On Mon, Feb 28, 2011 at 12:37 PM, chen jia <chen_1...@fisher.osu.edu> wrote: > When I extract data from SQLite to R, the data types (or modes) of the > extracted data seems to be determined by the value of the first row. > Please see the following example.
It would help to provide the output of sessionInfo() as well as the schema definition for the table in SQLite (or at least description of how it was created). Here's an example that works as you'd like: > library(RSQLite) > db = dbConnect(SQLite(), dbname = ":memory:") > dbGetQuery(db, "create table t (a int, b real, c text)") > df = data.frame(a=c(NA, 1L, 2L), b=c(NA, 1.1, 2.2), c=c(NA, "x", "y"),stringsAsFactors=FALSE) > df a b c 1 NA NA <NA> 2 1 1.1 x 3 2 2.2 y > dbGetPreparedQuery(db, "insert into t values (?, ?, ?)", df) > dbGetQuery(db, "select * from t") a b c 1 NA NA <NA> 2 1 1.1 x 3 2 2.2 y > sapply(dbGetQuery(db, "select * from t"), typeof) a b c "integer" "double" "character" > sapply(dbGetQuery(db, "select * from t limit 1"), typeof) a b c "integer" "double" "character" > sapply(dbGetQuery(db, "select a from t limit 1"), typeof) a "integer" > sapply(dbGetQuery(db, "select a from t limit 2"), typeof) a "integer" > sapply(dbGetQuery(db, "select a from t limit 1"), typeof) a "integer" > sessionInfo() R version 2.11.1 (2010-05-31) 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 datasets utils methods base other attached packages: [1] RSQLite_0.9-4 DBI_0.2-5 loaded via a namespace (and not attached): [1] tools_2.11.1 -- Seth Falcon | @sfalcon | http://userprimary.net/ ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.