Looping code for multiple db3 files in R - r

Question

I'm trying to import a number of .db3 files, and rbind them together for further analysis. I'm having no troubles importing a single .db3 file, but my rbind won't work, despite it working fine for .csv files. Where have I gone wrong?
df <- c()
for (x in list.files(pattern="*.db3")){
sqlite <- dbDriver("SQLite")
mydb <- dbConnect(sqlite, x)
dbListTables(mydb)
results <- dbSendQuery(mydb, "SELECT * FROM gps_data")
data = fetch(results, n = -1)
data$Label <- factor(x)
data <- rbind(df, data)
}
Any help you can offer would be great!

Answer 1

Let's have a close look at that rbind call at the end of your loop:
df <- c()
for (x in list.files(pattern="*.db3")){
sqlite <- dbDriver("SQLite")
mydb <- dbConnect(sqlite, x)
dbListTables(mydb)
results <- dbSendQuery(mydb, "SELECT * FROM gps_data")
data = fetch(results, n = -1)
data$Label <- factor(x)
data <- rbind(df, data)
}
You've created the object df, then you're binding data to the end of it and using that to override the existing data (note df hasn't changed). Great. Now your loop starts again, creating a new data object, and binding it to.... df. Doh! It's a simple error, but you're binding things in the wrong order. Try changing that last line to:
df <- rbind( df, data )
and see how it goes.
What you'll be doing differently is overwriting df over and over, making it bigger each time. When you overwrote data, you went back and recreated it anew, throwing away what you'd just done.