Read an Excel file directly from a R script

Question

How can I read an Excel file directly into R? Or should I first export the data to a text- or CSV file and import that file into R?

Answer 1

Expanding on the answer provided by @Mikko you can use a neat trick to speed things up without having to "know" your column classes ahead of time. Simply use read.xlsx to grab a limited number of records to determine the classes and then followed it up with read.xlsx2

Example

# just the first 50 rows should do...
df.temp <- read.xlsx("filename.xlsx", 1, startRow=1, endRow=50) 
df.real <- read.xlsx2("filename.xlsx", 1, 
                      colClasses=as.vector(sapply(df.temp, mode)))