read excel sheets

read.xls.R

#' best package to read excel files is gdata
#' which works with both .xls and .xlsx

#' windows: follow instructions here: 
#' http://cran.r-project.org/web/packages/gdata/INSTALL
library(gdata)
xlsx_file <- "myfile.xls"
sheet1 <- read.xls(xlsx_file,
                   sheet = "Sheet1", 
                   stringsAsFactors = FALSE, 
                   na.strings = "NA")

#' OR:
library(xlsx)
xlsx_file <- "myfile.xls"
text_data <- read.xlsx(xlsx_file, sheetName = "Sheet1")